Polyamide resin composition

ABSTRACT

The present invention relates to a polyamide resin composition comprising polyamide (X) comprising a diamine unit containing 70 mol % or more of a metaxylylenediamine unit and a dicarboxylic acid unit and an alkali compound (A), wherein the following equations (1) to (4) are satisfied: 
       10≦([COOH]—[NH 2 ])≦80  (1)
 
       0.32≦P&lt;6.46  (2)
 
       0.50≦M&lt;17.00  (3)
 
       2≦M/P≦3  (4)
 
     wherein [COOH] represents a concentration (μeq/g) of a terminal carboxyl group in the polyamide (X); [NH 2 ] represents a concentration (μeq/g) of a terminal amino group in the polyamide (X); P represents a mole concentration (μmol/g) of a phosphorus atom contained per g of the polyamide resin composition; and M represents a sum (μmol/g) of values obtained by multiplying a mole concentration of an alkali metal atom and a mole concentration of an alkaline earth metal atom each contained per g of the polyamide resin composition by valencies thereof respectively.

TECHNICAL FIELD

The present invention relates to a polyamide resin composition,specifically to a polyamide resin composition which is industriallyuseful as a packaging material and a material for fibers.

BACKGROUND ART

Polyamide having a metaxylylene group in a polymer principal chain has ahigh rigidity and is widely used as a molding material, and in additionthereto, it is excellent as well in a performance of cutting off oxygen,carbon dioxide and the like and is also used as a gas-barrier materialfor various packaging materials such as bottles, sheets, films and thelike. Particularly in polyamide used for applications such as bottles,sheets, films, fibers and the like, attentions are paid to mixing offoreign matters. Due to that the molded and processed products aretransparent and thin, that a high level and delicate mold processingtechnology is required and that foreign matters are very highly likelyto damage the performances of the molded and processed products, mixingof foreign matters brings about the inferior appearance, an increase ina rate of generating defects such as breaking and the like attributableto foreign matter-generating sites and a reduction in the productivity.

Foreign matters originating in polyamide include powders called a fine,thin films called a froth, yellowed matters and carbides produced bythermal degradation and gelatinous matters. It is the bestcountermeasure to inhibit the above foreign matters from being produced,but when they are inevitably produced, they have to be separated andremoved from the pelletized products. The powders and the thin films areusually removed by wind selection, and the yellowed matters and thecarbides can be removed by a screening equipment using an opticalsensor. Various separating equipments are commercially available, andthe sure removing effects can be expected.

On the other hand, gels are estimated to be produced due to that themolecules are damaged (the polymer molecules are degraded by radicalsgenerated) during polymerization and mold processing to bring aboutabnormal reactions (turned into three-dimensional polymers) such asgrowing of non-linear molecules and the like and that they are turnedinto an extremely high molecular weight as compared with those of otherpolyamide molecules. Accordingly, a thermal history has to be reduced tothe utmost in the production step in order to obtain polyamidecontaining less gel, and measurements such as adding a heat stabilizeror an antioxidant are carried out. However, some of the above additivesshow a catalytic effect to amidation reaction, and on the contrary, theyexpedite excessively polymerization reaction to bring about an increasein gels in a certain case. Accordingly, the reaction is carried outusually while maintaining a balance between promotion and inhibition ofthe reaction by adding a specific amount of an alkali compound havingfurther a reaction inhibitory effect.

Gels produced in a melt polymerization step can be removed by a filterand the like, but the gels are turned into fine particles by a flowpressure and pass through the filter in many cases. Further, gels arelikely to be produced as well in solid phase polymerization carried outin producing high viscosity products, and therefore it is almostimpossible to completely remove them.

Further, gels can be produced as well in melting in mold processingother than during production of polyamide. Even when used is polyamidein which a marked difference in a production amount of gels is notobserved in evaluating a quality of the polyamide after productionthereof, the difference is exerted in a certain case in mold processing,and a cause thereof is estimated to be attributable to that an excessivethermal history is applied to a part of the polymer in staying partsthereof such as screw grooves, a filter, a die and the like in moldprocessing. Further, if a polyamide resin stays in an inside of amolding machine for a long time in molding a bottle, a degraded matterof the resin is turned into burnt deposits, and they are mixed in theproduct to deteriorate a yield of the product, or the burnt depositsclog flow channels in an inside of the molding machine to make itimpossible to carry out the molding in a certain case. When burntdeposits are generated, it is necessary to use a purging agent or todisassemble and clean the die, and the stable production is prevented.It can be found from the above matters that it is important forobtaining finally mold processed articles having less gel and burntdeposit to produce polyamide having further less gel and a higher gradeand design a mold processing apparatus having very small staying parts.

It is necessary for producing polyamide having further less gel toinhibit a thermal history in the production, control a balance betweenaddition of an effective stabilizer and an amount thereof and removegels produced as well in melt polymerization and solid phasepolymerization, but the effects thereof have been limited. Further, indesigning a mold processing apparatus, it is possible to reduceproduction of gels by subjecting, for example, metal parts which arebrought into contact with the resin to plating treatment, but it isdifficult in terms of constitution of the apparatus to completelyeliminate the staying parts. Further, the respective molding apparatuseshave to be subjected to the treatment, and it is lacking in thepossibility thereof in terms of the versatility and the cost.Particularly in polyamide comprising a diamine component in whichxylylenediamine is a principal component, radicals are liable to beproduced in a benzylmethylene site of xylylenediamine, and production ofgels provides more serious problems than in other polyamides.

Patent document 1 discloses a method in which at least one selected froma lubricant, an organic phosphorus base stabilizer, a hindered phenolcompound and a hindered amine compound is added in an amount of 0.0005to 0.5 parts by mass in mold and processing polyamide to thereby inhibitgels from being produced.

Patent document 2 discloses a method in which fish eyes are inhibitedfrom being produced in mold processing by adding 0.001 to 0.015 parts bymass of a metal salt of a higher fatty acid and a polyhydric alcoholcompound in order to enhance a lubricity of polyamide to inhibitshearing heat from being generated in the mold processing.

Patent document 3 discloses a method in which 50 to 1,000 ppm by weightof a phosphinic acid compound or a phosphonous acid compound and 1 to 5mole times of an alkali compound based on a concentration of phosphorusatoms contained are added to thereby inhibit gels from being produced.

Patent documents 4 and 5 disclose methods in which a phosphorus basecompound and an alkali metal salt are added in a fixed balance tothereby inhibit a back pressure of a filter from being elevated by aphosphorus-modified product and inhibit gels from being produced.

Patent documents 6 and 7 disclose methods in which the amounts ofpyrophosphoric acid and other phosphorus base compounds contained inpolyamide are controlled to thereby inhibit a back pressure of a filterfrom being elevated by a phosphorus-modified product and inhibit gelsfrom being produced.

CITATION LIST Patent Documents

-   [Patent document 1] JP-A-2001-164109-   [Patent document 2] JP-B-3808847-   [Patent document 3] JP-A-49-38950-   [Patent document 4] JP-A-2005-194328-   [Patent document 5] JP-A-2005-194330-   [Patent document 6] JP-A-2007-92053-   [Patent document 7] JP-A-2007-92054

SUMMARY OF INVENTION Technical Problem

However, the method described in Patent document 1 is short of effectswhen the results described in the examples are observed in terms of apractical aspect, and specific grounds for inhibiting gels from beingproduced in the respective additives are scarcely referred to. Further,it is not at all described in Patent document 2 that a change itself ina quality of polyamide is inhibited. A method for determining a gelproduction amount in Patent document 3 is unsatisfactory in imitation ofan actual mold processing environment, and in fact, production of gelscan not be sufficiently inhibited by the method described in Patentdocument 3. In Patent documents 4 to 7, the phosphorus base compound andthe alkali metal salt are described within the limit of adding them inthe melt polymerization, and production of gels in mold processing cannot be sufficiently inhibited by these methods. Furthermore, somemethods in which gels or fish eyes are inhibited from being produced inmold processing have been studied from viewpoint of a material, but auseful method in which burnt deposits are inhibited from being producedin molding a bottle have not been discovered.

A problem to be solved by the present invention is to provide apolyamide resin composition which has a good color tone and whichproduces less gel and burnt deposit in mold processing, a productionprocess for the same, and a multilayer molded article prepared by usingthe above polyamide resin composition.

Solution to Problem

The present invention provides a polyamide resin composition, aproduction process for the same and a multilayer molded article eachshown below. [1] A polyamide resin composition comprising polyamide (X)comprising a diamine unit containing 70 mol % or more of ametaxylylenediamine unit and a dicarboxylic acid unit and an alkalicompound (A), wherein the following equations (1) to (4) are satisfied:

10≦([COOH]—[NH₂])≦80  (1)

0 32≦P<6.46  (2)

0.50≦M<17.00  (3)

2≦M/P≦3  (4)

wherein [COOH] represents a concentration (μeq/g) of a terminal carboxylgroup in the polyamide (X); [NH₂] represents a concentration (μeq/g) ofa terminal amino group in the polyamide (X); P represents a moleconcentration (μmol/g) of a phosphorus atom contained per g of thepolyamide resin composition; and M represents a sum (μmol/g) of valuesobtained by multiplying a mole concentration of an alkali metal atom anda mole concentration of an alkaline earth metal atom each contained perg of the polyamide resin composition by valencies thereof respectively.[2] A production process for the polyamide resin composition accordingto the above item [1], comprising:

(a) a step in which diamine containing 70 mol % or more ofmetaxylylenediamine and dicarboxylic acid are subjected topolycondensation under the presence of a phosphorus atom-containingcompound (B) to obtain polyamide (X) and

(b) a step in which an alkali compound (A) is added to the polyamide (X)obtained in the step (a) described above.

[3] A multilayer molded article comprising an outermost layer, aninnermost layer and at least one gas-barrier layer between the outermostlayer and the innermost layer, wherein the outermost layer and theinnermost layer are constituted from a polyester resin comprising adicarboxylic acid unit containing 80 mol % or more of a terephthalicacid unit and a diol unit containing 80 mol % or more of an ethyleneglycol unit, and the gas-barrier layer is constituted from the polyamideresin composition according to the above item [1].

Advantageous Effects of Invention

According to the present invention, a polyamide resin composition whichhas a good color tone and which produces less gelatinous substance inproduction and mold processing can be provided. Further, the multilayermolded article of the present invention contains less burnt deposit andhas a very high industrial value as a multilayer bottle and the like.

DESCRIPTION OF EMBODIMENTS

The polyamide resin composition of the present invention comprisespolyamide (X) comprising a diamine unit containing 70 mol % or more of ametaxylylenediamine unit and a dicarboxylic acid unit and an alkalicompound (A), wherein the following equations (1) to (4) are satisfied:

10≦([COOH]—[NH₂])≦80  (1)

0 32≦P<6.46  (2)

0.50≦M<17.00  (3)

2≦M/P≦3  (4)

wherein [COOH] represents a concentration (μeq/g) of a terminal carboxylgroup in the polyamide (X); [NH₂] represents a concentration (μeq/g) ofa terminal amino group in the polyamide (X); P represents a moleconcentration (μmol/g) of a phosphorus atom contained per g of thepolyamide resin composition; and M represents a sum (μmol/g) of valuesobtained by multiplying a mole concentration of an alkali metal atom anda mole concentration of an alkaline earth metal atom each contained perg of the polyamide resin composition by valencies thereof respectively.

The alkali compound is used, as described above, as a neutralizing agentfor a phosphorus base compound added in the polymerization. However, ause amount thereof in the polymerization of the polyamide is limitedfrom the viewpoint of a balance with the phosphorus base compound. Theinventors of the present invention have made earnest studies, and as aresult, found that gels can be inhibited from being produced in moldprocessing by adding the alkali compound in the mold processing afterpolymerizing the polyamide to elevate a concentration thereof andallowing an end group concentration of the polyamide, a phosphorus atomconcentration and an alkali metal atom concentration to fall in specificnumerical value ranges; an amount of gels produced is small even if astaying situation of the molten polyamide continues over a long periodof time; and the resulting molded article is decreased in gels andcoloring and has a good appearance. The present invention has beencompleted based on the above findings.

<Polyamide (X)>

The diamine unit constituting the polyamide (X) contains 70 mol % ormore of the metaxylylenediamine unit, and it contains preferably 80 mol% or more, more preferably 90 mol % or more. If the metaxylylenediamineunit in the diamine unit accounts for 70 mol % or more, the polyamide(X) can exert an excellent gas-barrier property. Further, the polyamide(X) exerts characteristics excellent in a co-injection moldability and aco-stretching blow moldability with a polyester resin (principallypolyethylene terephthalate) and has a good formability.

Capable of being shown as the examples of compounds other than themetaxylylenediamine unit which can constitute the diamine are aliphaticdiamines such as tetramethylenediamine, pentamethylenediamine,2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine,octamethylenediamine, nonamethylenediamine, decamethylenediamine,dodecamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine,2,4,4-trimethyl-hexamethylenediamine and the like; alicyclic diaminessuch as 1,3-bis(aminomethyl)cyclohexane,1,4-bis(aminomethyl)cyclohexane, 1,3-diaminocyclohexane,1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane,2,2-bis(4-aminocyclohexyl)propane, bis(aminomethyl)decalin,bis(aminomethyl)tricyclodecane and the like; and diamines havingaromatic rings, such as bis(4-aminophenyl)ether, paraphenylenediamine,paraxylylenediamine, bis(aminomethyl)naphthalene and the like. However,they shall not be restricted to the above compounds.

Capable of being shown as the examples of compounds which can constitutethe dicarboxylic acid unit constituting the polyamide (X) are aliphaticdicarboxylic acids such as succinic acid, glutaric acid, pimelic acid,adipic acid, suberic acid, azelaic acid, sebacic acid, undecandioicacid, dodecanedioic acid, dimer acid and the like; alicyclicdicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and thelike; and aromatic dicarboxylic acids such as terephthalic acid,isophthalic acid, orthophthalic acid, xylylenedicarboxylic acid,naphthalenedicarboxylic acid and the like. However, they shall not berestricted to the above compounds. Among them, adipic acid and sebacicacid are preferred.

Polyamide comprising a diamine unit containing 70 mol % or more of ametaxylylenediamine unit and a dicarboxylic acid unit containing 70 mol% or more, preferably 80 mol % or more and more preferably 90 mol % ormore of an adipic acid unit can be shown as the example of the polyamide(X) which can be preferably used in the present invention. If 70 mol %or more of the adipic acid is contained in the dicarboxylic acid unit, areduction in the gas-barrier property and an excessive reduction in thecrystallinity can be avoided. At least one of α,ω-linear aliphaticdicarboxylic acids having 4 to 20 carbon atoms is preferably used as acompound which can constitute the dicarboxylic acid unit other than theadipic acid unit.

Further, polyamide comprising a diamine unit containing 70 mol % or moreof a metaxylylenediamine unit and a dicarboxylic acid unit containing 70to 99 mol % of an adipic acid unit and 1 to 30 mol % of an isophthalicacid unit can also be shown as the example of the polyamide (X) whichcan be preferably used in the present invention. Addition of theisophthalic acid unit as the dicarboxylic acid unit makes it possible toreduce the melting point and lower the mold processing temperature andtherefore makes it possible to reduce a thermal history during moldingthe polyamide resin composition and inhibit gels and burnt deposits frombeing produced.

Further, polyamide comprising a diamine unit containing 70 mol % or moreof a metaxylylenediamine unit and a dicarboxylic acid unit containing 70mol % or more, preferably 80 mol % or more and more preferably 90 mol %or more of a sebacic acid unit can also be shown as the example of thepolyamide (X) which can be preferably used in the present invention. If70 mol % or more of the sebacic acid unit is contained in thedicarboxylic acid unit, a reduction in the gas-barrier property and anexcessive reduction in the crystallinity can be avoided. In additionthereto, the melting point can be reduced, and the mold processingtemperature can be lowered. Further, gels and burnt deposits can beinhibited from being produced. At least one of α,ω-linear aliphaticdicarboxylic acids having 4 to 20 carbon atoms is preferably used as acompound other than the sebacic acid unit which can constitute thedicarboxylic acid unit.

In addition to the diamines and the dicarboxylic acids each describedabove, lactams such as ε-caprolactam, laurolactam and the like,aliphatic aminocarboxylic acids such as aminocaproic acid,aminoundecanoic acid and the like and aromatic aminocarboxylic acidssuch as p-aminomethylbenzoic acid and the like can also be used as acopolymerization component for a component constituting the polyamide(X) as long as the effects of the present invention are not damaged.

From viewpoint of moldability in molding of multilayer molded articles,a number average molecular weight of the polyamide (X) is preferably10,000 to 50,000, more preferably 15,000 to 45,000 and furtherpreferably 20,000 to 40,000, and it is suitably selected according tothe uses and the molding method of the polyamide resin composition. In acase where the fluidity of some extent is required in the production,for example, a case of the use such as a film and the like, a numberaverage molecular weight of the polyamide (X) is preferably 20,000 to30,000. In a case where the melt strength is required in the production,for example, a case of the use such as a sheet and the like, a numberaverage molecular weight of the polyamide (X) is preferably 30,000 to40,000.

A number average molecular weight of the polyamide (X) is calculatedfrom the following equation (5):

Number average molecular weight=2×1,000,000/([COOH]+[NH₂])  (5)

wherein [COOH] represents a concentration (μmol/g) of a terminalcarboxyl group in the polyamide (X), and [NH₂] represents aconcentration (μmol/g) of a terminal amino group in the polyamide (X).

In the present invention, a value calculated by dissolving the polyamidein a phenol/ethanol mixed solvent and neutralizing and titrating theresulting solution with a diluted hydrochloric acid aqueous solution isused for the terminal amino group concentration, and a value calculatedby dissolving the polyamide in benzyl alcohol and neutralizing andtitrating the resulting solution with a sodium hydroxide aqueoussolution is used for the terminal carboxyl group concentration.

In an end group balance in the polyamide (X) in the present invention,that is, a balance between the terminal carboxyl group concentration[COOH] and the terminal amino group concentration [NH₂], the terminalcarboxyl group concentration is higher than the terminal amino groupconcentration, and a difference ([COOH]—[NH₂]) between the terminalcarboxyl group concentration [COOH] and the terminal amino groupconcentration [NH₂] is 10 to 80 μeq/g, preferably 20 to 70 μeq/g andmore preferably 25 to 60 μeq/g.

To be theoretical, it is considered that the amide group productionreaction velocity is the fastest when a value of [COOH]—[NH₂] is 0, sothat the polymerization time in the melt state and the solid phase stateis the shortest and that the damage of the polyamide molecule iscontrolled to the lowest limit. In fact, however, when a value of[COOH]—[NH₂] is less than 10 μeq/g, in other words, when the terminalamino group concentration is excessive, an increase in the viscositywhich is considered to originate in reaction other than the amide groupproduction reaction is brought about in the solid phase polymerization.Accordingly, staying of the resin is liable to be brought about in aninside of the flow channels in mold processing of the polyamide (X), andgels and burnt deposits are liable to be produced.

In the present invention, controlling a value of [COOH]—[NH₂] to 10 to80 μeq/g makes it possible to maintain the amide group productionreaction velocity to a practical velocity and shorten the polymerizationtime in the melt state and the solid phase state to such an extent thatthe polyamide molecule can be inhibited from being damaged. Further,production of gels and burnt deposits can be reduced in mold processing.

<Alkali Compound (A)>

The polyamide resin composition of the present invention contains thealkali compound (A) from the viewpoint of preventing gels and burntdeposits from being produced in the mold processing.

The preferred specific examples of the alkali compound (A) used in thepresent invention include hydroxides, hydrides, alkoxides, carbonates,hydrogencarbonates and carboxylates of alkali metals and alkaline earthmetals, but they shall not specifically be restricted to the abovecompounds. The preferred specific examples of the alkali metals and thealkaline earth metals include sodium, potassium, lithium, rubidium,cesium, magnesium, calcium and the like.

The hydroxides of the alkali metals and the alkaline earth metalsinclude, for example, lithium hydroxide, sodium hydroxide, potassiumhydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide,calcium hydroxide and the like.

The hydrides of the alkali metals and the alkaline earth metals include,for example, lithium hydride, sodium hydride, potassium hydride and thelike.

The alkali metal alkoxides and the alkaline earth metal alkoxides arepreferably alkoxides having 1 to 4 carbon atoms and include, forexample, sodium methoxide, potassium methoxide, lithium methoxide,magnesium methoxide, calcium methoxide, sodium ethoxide, potassiumethoxide, lithium ethoxide, magnesium ethoxide, calcium ethoxide, sodiumt-butoxide, potassium t-butoxide, lithium t-butoxide, magnesiumt-butoxide, calcium t-butoxide and the like.

The carbonates and the hydrogencarbonates of the alkali metals and thealkaline earth metals include, for example, sodium carbonate, sodiumbicarbonate, potassium carbonate, potassium bicarbonate, lithiumcarbonate, calcium carbonate, magnesium carbonate, sodiumhydrogencarbonate, calcium hydrogencarbonate and the like, and anhydroussalts and hydrate salts thereof can be used.

The carboxylates of the alkali metals and the alkaline earth metals arepreferably carboxylates having 1 to 10 carbon atoms, and anhydrous saltsand hydrate salts thereof can be used. The specific examples of thecarboxylic acids include, for example, linear saturated fatty acids suchas formic acid, acetic acid, propionic acid, butyric acid, valeric acid,caproic acid, enanthic acid, capric acid, pelargonic acid, lauric acid,myristic acid, palmitic acid, stearic acid, eicosanoic acid, behenicacid, montanic acid, triacontanoic acid and the like; fatty acidderivatives such as 12-hydroxystearic acid and the like; aliphaticdicarboxylic acids such as oxalic acid, fumaric acid, maleic acid,succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid,azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid andthe like; hydroxy acids such as glycolic acid, lactic acid,hydroxybutyric acid, tartaric acid, malic acid, citric acid, isocitricacid, mevalonic acid and the like; and aromatic carboxylic acids such asbenzoic acid, terephthalic acid, isophthalic acid, orthophthalic acid,pyromellitic acid, trimellitic acid, xylylenedicarboxylic acid,naphthalenedicarboxylic acid and the like.

The alkali compound (A) used in the present invention may be used in asingle kind of the compounds described above or in combination of two ormore kinds thereof. Among the compounds described above, carboxylateshaving 10 or less carbon atoms of the alkali metal are preferred fromthe viewpoints of a dispersibility in the polyamide (X) and an effect ofinhibiting gels and burnt deposits from being produced, and sodiumacetate and sodium acetate trihydrate are more preferred from theviewpoints of an economical efficiency and an effect of inhibiting gelsand burnt deposits from being produced. Further, sodium carbonate ispreferred as well, and sodium carbonate decahydrate is more preferred.In particular, sodium acetate trihydrate and sodium carbonatedecahydrate are preferred since they have a low melting point and areimproved in a dispersibility in the polyamide (X).

<Phosphorus Atom-Containing Compound (B)>

The phosphorus atom-containing compound (B) is used in the production ofthe polyamide (X) from the viewpoints of enhancing the processingstability in the melt processing and preventing the polyamide (X) frombeing colored. Accordingly, a phosphorus component is contained in thepolyamide resin composition of the present invention.

The preferred specific examples of the phosphorus atom-containingcompound (B) include hypophosphorous acid compounds (called as wellphosphinic acid compounds or phosphinous acid compounds), phosphorousacid compounds (called as well phosphonic acid compounds) and the like,but they shall not specifically be restricted to the above compounds.The phosphorus atom-containing compound (B) may be metal salts or alkalimetal salts.

The specific examples of the hypophosphorous acid compounds includehypophosphorous acid; hypophosphorous acid metal salts such as sodiumhypophosphite, potassium hypophosphite, lithium hypophosphite and thelike; hypophosphorous acid compounds such as ethyl hypophosphite,dimethyl phosphinate, phenyl methyl phosphinate, phenyl phosphinate,ethyl phenylphosphinate and the like; phenylphosphinous acid metal saltssuch as sodium phenylphosphinate, potassium phenylphosphinate, lithiumphenylphosphinate and the like.

The specific examples of the phosphorous acid compounds includephosphorous acid and pyrophosphoric acid; phosphorous acid metal saltssuch as sodium hydrogenphosphite, sodium phosphite and the like;phosphorous acid compounds such as triethyl phosphite, triphenylphosphite, ethylphosphonic acid, phenylphosphonic acid, diethylphenylphosphonate and the like; phenylphosphonic acid metal salts suchas sodium ethylphosphonate, potassium ethylphosphonate, sodiumphenylphosphonate, potassium phenylphosphonate, lithiumphenylphosphonate and the like.

The phosphorus atom-containing compound (B) may be used in a single kindof the compounds described above or in combination of two or more kindsthereof. Among the compounds described above, hypophosphorous acid metalsalts such as sodium hypophosphite, potassium hypophosphite, lithiumhypophosphite and the like are preferred from the viewpoints of aneffect of accelerating the polymerization reaction of the polyamide (X)and an effect of preventing the coloring, and sodium hypophosphite ismore preferred.

<Mole Concentrations of Phosphorus Atom, Alkali Metal Atom and AlkalineEarth Metal Atom>

A mole concentration P of a phosphorus atom contained per g of thepolyamide resin composition of the present invention is 0.32 μmol/g ormore and less than 6.46 μmol/g, preferably 0.50 to 6.00 μmol/g and morepreferably 0.65 to 5.17 μmol/g from the viewpoints of enhancing theprocessing stability in the melt processing and preventing the polyamide(X) from being colored. If P is too low, the polyamide is colored duringthe polymerization or the molding in a certain case. Also, if P is 6.46μmol/g or more, the polyamide is observed to be improved in coloring,but gelation reaction is accelerated in synthesis of the polyamide, andthe back pressure is elevated in the mold processing in a certain caseby clogging of a filter which is considered to be attributable to athermally modified product of the phosphorus atom-containing compound(B).

A sum M of values obtained by multiplying a mole concentration of analkali metal atom and a mole concentration of an alkaline earth metalatom each contained per g of the polyamide resin composition of thepresent invention by valencies thereof respectively (hereinafterreferred to as “a total mole concentration of an alkali metal atom andan alkaline earth metal atom”) is 0.50 μmol/g or more and less than17.00 μmol/g, preferably 1.00 to 15.00 μmol/g and more preferably 2.00to 12.00 μmol/g from the viewpoints of preventing gels and burntdeposits from being produced in the melt processing.

It is estimated that controlling M to 0.50 μmol/g or more makes itpossible to retard an increase in a molecular weight of the polyamidewhich is brought about by heating when the polyamide is molten toinhibit gels and burnt deposits from being produced. On the other hand,if M is 17.00 μmol/g or more, inferior molding is caused in a certaincase by a reduction in the viscosity. In addition thereto, coloring andwhitening are brought about, and the alkali compound (A) is deposited ina certain case.

As described above, the alkali metal salt is used as the phosphorusatom-containing compound (B) in a certain case. Further, as describedlater, in the production of the polyamide resin composition of thepresent invention, the alkali metal compound (C) is added, if necessary,in the polycondensation of the polyamide, and the alkali compound (A) isadded after the polycondensation of the polyamide. Accordingly, M is asum (μmol/g) of values obtained by multiplying the mole concentrationsof all of an alkali metal atom and an alkaline earth metal atom eachcontained per g of the polyamide resin composition by valencies thereofrespectively.

In the present invention, a value (M/P) obtained by dividing a totalmole concentration M of an alkali metal atom and an alkaline earth metalatom each contained per g of the polyamide resin composition of thepresent invention by a mole concentration P of a phosphorus atomcontained per g of the polyamide resin composition of the presentinvention is 2 or more and 3 or less, preferably 2.1 to 2.9 and morepreferably 2.2 to 2.8 from the viewpoints of preventing production ofgels and burnt deposits which is brought about in the melt processing,enhancing the processing stability in the melt processing and preventingthe polyamide (X) from being colored. If M/P is less than 2, an effectof inhibiting the amidation reaction by the alkali compound (A) is shortin a certain case, and gels in the polyamide is increased in some cases.On the other hand, if M/P exceeds 3, inferior molding is caused in acertain case by a reduction in the viscosity. In addition thereto,coloring and whitening are brought about in some cases, and the alkalicompound (A) is deposited in a certain case.

[Production Process of Polyamide Resin Composition]

The polyamide resin composition of the present invention can be producedby a process comprising the following steps (a) and (b):

Step (a): a step in which diamine containing 70 mol % or more ofmetaxylylenediamine and dicarboxylic acid are subjected topolycondensation under the presence of the phosphorus atom-containingcompound (B) to obtain the polyamide (X); and

Step (b): a step in which the alkali compound (A) is added to thepolyamide (X) obtained in the step (a) described above.

<Step (a)>

The step (a) is a step in which diamine containing 70 mol % or more ofmetaxylylenediamine and dicarboxylic acid are subjected topolycondensation under the presence of the phosphorus atom-containingcompound (B) to obtain the polyamide (X). Subjecting the polyamide (X)to polycondensation under the presence of the phosphorus atom-containingcompound (B) makes it possible to enhance the processing stability inthe melt processing and prevent the polyamide (X) from being colored.

A use amount of the phosphorus atom-containing compound (B) is an amountin which a mole concentration P of a phosphorus atom contained per g ofthe polyamide resin composition falls in the range described above.

The production process for the polyamide (X) shall not specifically berestricted as long as it is carried out under the presence of thephosphorus atom-containing compound (B), and it can be carried out by anoptional method on optional polymerization conditions. The polyamide (X)can be produced, for example, by heating a nylon salt comprising adiamine component (for example, metaxylylenediamine) and a dicarboxylicacid component (for example, adipic acid) under the presence of water ina pressurizing state to polymerize them in a melting state whileremoving added water and condensation water.

Further, the polyamide (X) can be produced as well by a method in whichthe diamine component (for example, metaxylylenediamine) is addeddirectly to the dicarboxylic acid component (for example, adipic acid)staying in a melting state to subject them to polycondensation under anatmospheric pressure. In the above case, the diamine component iscontinuously added to the dicarboxylic acid component in order tomaintain the reaction system in an even liquid state, and during thattime, the polycondensation is promoted wile heating the reaction systemso that the reaction temperature is not lower than the melting points ofoligoamide and polyamide each produced.

A small amount of monoamine and monocarboxylic acid may be added as amolecular weight controlling agent in the polycondensation of thepolyamide (X).

Further, the polyamide (X) may be subjected to polycondensation bysubjecting to solid phase polymerization after produced by a meltpolymerization method. The solid phase polymerization shall notspecifically be restricted, and it can be carried out by an optionalmethod on optional polymerization conditions.

The polycondensation of the polyamide (X) is carried out preferablyunder the presence of the phosphorus atom-containing compound (B) andthe alkali metal compound (C). A sufficiently large amount of thephosphorus atom-containing compound (B) has to be added in order toprevent the polyamide (X) from being colored during thepolycondensation, but if a use amount of the phosphorus atom-containingcompound (B) is too large, not only the amidation reaction rate isaccelerated too much to make it difficult to control the polymerization,but also production of gels and burnt deposits is likely to be broughtabout in the mold processing. Accordingly, the alkali metal compound (C)is preferably allowed to be coexistent from the viewpoint of controllingthe amidation reaction rate.

The alkali metal compound (C) shall not specifically be restricted, andalkali metal hydroxides and alkali metal acetic acid salts can be listedas the preferred specific examples thereof. Lithium hydroxide, sodiumhydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxidecan be listed as the alkali metal hydroxides, and lithium acetate,sodium acetate, potassium acetate, rubidium acetate and cesium acetatecan be listed as the alkali metal acetic acid salts.

When the alkali metal compound (C) is used in obtaining the polyamide(X) by polycondensation, a use amount of the alkali metal compound (C)falls in a range of preferably 0.5 to 1, more preferably 0.55 to 0.95and further preferably 0.6 to 0.9 in terms of a value obtained bydividing a mole number of the alkali metal compound (C) by a mole numberof the phosphorus atom-containing compound (B) from the viewpoint ofinhibiting gels and burnt deposits from being produced.

<Step (b)>

The step (b) is a step in which the alkali compound (A) is added to thepolyamide (x) obtained in the step (a) described above.

A molded article obtained by subjecting the polyamide (X) as it is tomold processing is excellent in properties and appearance immediatelyafter starting molding, but generation of gels and burnt deposits isincreased as the molding processing work continues for a long time, andthe quality of the product becomes unstable in a certain case.Particularly in a case of the film, it is broken by the gels, and theapparatus can not help being stopped, so that the production efficiencyis deteriorated. This is estimated to take place due to that thepolyamide continues to stay locally in a melt-kneading part through adice, whereby it is excessively heated and gelatinized and that the gelsproduced flow out. Further, in molding a bottle, the polyamide stayingin an inside of a flow channel in a molding machine is deteriorated byexcessively heating to result in generating burnt deposits, and theyclog the flow channel and are mixed in the bottle of the product todeteriorate the quality of the bottle. In order to meet the abovematters, the alkali compound (A) is added to the resulting polyamide (X)in the present invention in order to prevent gels and burnt depositsbrought about in the mold processing from being produced.

The present inventors have found from measurement of the molecularweight by a gel permeation chromatography that continuous heating of thepolyamide in a molten state promotes polarization of the polyamide intoa low molecular weight and a high molecular weight and that the more thehigh molecular weight component is, the more the production amount ofgels and burnt deposits is increased in the mold processing of thepolyamide. A mechanism of generating burnt deposits is not apparent, andit is estimated that the polyamide stays and is excessively heated in aninside of the apparatus, that is, flow channel parts of the molten resinsuch as a screw, an inside of the extruding equipment, an inside of thedie, a hot runner and the like, whereby a molecular weight thereof iselevated, so that the polyamide is deteriorated in flowing in the aboveparts; accordingly, the polyamide is liable to stay more and more in theabove parts, and finally, the polyamide staying there is excessivelyheated to result in generating burnt deposits.

In contrast with this, the present inventors have found as well that thehigh molecular weight component is decreased by adding the alkalicompound (A) to the polyamide. The reasons thereof have not yet beenclarified and are estimated to be attributable to that particularlyprogress of amidation brought about during molding the polyamide resincomposition is retarded by adding the alkali compound (A) to result ininhibiting an increase in the molecular weight; flow in an inside of theapparatus is maintained in a good state, and the polyamide can beprevented from being excessively heated; and as a result thereof, gelsand burnt deposits are inhibited from being produced.

As described above, the same compounds as the examples of the alkalimetal compound (C) which can be added in producing the polyamide (X) areshown as the examples of the alkali compound (A). However, if the alkalimetal compound (C) is excessively added in the melt polymerization, aneffect of accelerating the amidation reaction of the phosphorusatom-containing compound (B) is inhibited too much to retard progress ofthe polycondensation, and the thermal history in producing the polyamidegrows large to increase gels and burnt deposits in the mold processingof the polyamide in a certain case. Accordingly, increasing an amount ofthe alkali metal compound (C) added in producing the polyamide (X) bymelt-polymerizing the monomer can not play a role of preventing gels andburnt deposits from being produced in the mold processing. In contrastwith this, gels and burnt deposits can effectively be prevented frombeing produced in the mold processing in the present invention by addingthe alkali compound (A) to the polyamide (X) obtained.

A use amount of the Alkali compound (A) is an amount in which a totalmole concentration M of an alkali metal atom and an alkaline earth metalatom each contained per g of the polyamide resin composition falls inthe range described above, and it is an amount in which M/P falls in therange described above.

A method for adding the alkali compound (A) to the polyamide (X) shallnot specifically be restricted, and it can be added by an optionalmethod. A method in which the polyamide (X) and the alkali compound (A)are molten and kneaded by means of an extrusion equipment is preferred.

Optional extrusion equipments such as a batch system kneading equipment,a kneader, a cokneader, a planetary extrusion equipment, a single shaftor double shaft extrusion equipment and the like can be used as theextrusion equipment. Among them, the single shaft extrusion equipmentand the double shaft extrusion equipment are preferably used from theviewpoints of a kneading ability and a productivity.

A means for supplying the polyamide (X) and the alkali compound (A) tothe extrusion equipment shall not specifically be restricted, and a beltfeeder, a screw feeder, a vibration feeder and the like can be used. Thepolyamide (X) and the alkali compound (A) may be supplied respectivelyby an independent feeder or may be dry-blended and then supplied.

A shape of the alkali compound (A) shall not specifically be restrictedas long as it can evenly be dispersed in the resin composition, and itmay be added as it is or may be added after molten by heating or may beadded after dissolved in a solvent. When added as it is in the form ofpowder, a particle diameter thereof is preferably 0.01 to 5.0 mm, morepreferably 0.02 to 3.0 mm. When the alkali compound (A) is dissolved ina solvent and then added, it can be added to the extrusion equipment bymeans of an equipment such as a feeder for adding a solution and thelike or can be blended in advance by means of a tumbler. Water andoptional organic solvents can be used as the solvent.

The polyamide (X) and the alkali compound (A) may be mixed directly inthe mold processing. Further, the polyamide (X) may be molten andkneaded with the alkali compound (A) having a high concentration bymeans of an extrusion equipment to prepare pellets, and the abovepellets may be blended with the polyamide (X) and subjected moldprocessing. Alternatively, the above pellets may be blended with thepolyamide (X) and subjected to solid phase polymerization, and then itmay be subjected to mold processing.

Further, in order to prevent separation of the polyamide (X) from thealkali compound (A) after dry-blended, a viscous liquid is adhered as aspreading agent to the polyamide (X), and then the alkali compound (A)may be added and mixed therewith. The spreading agent shall notspecifically be restricted, and surfactants and the like can be used.

In the preferred production process for the polyamide resin compositionof the present invention, the step (b) described above contains steps(b1) and (b2) shown below.

Step (b1): a step in which 90 to 99 parts by mass of the polyamide (X)and 10 to 1 part by mass of the alkali compound (A) are molten andkneaded by means of an extrusion equipment to obtain a polyamide masterbatch (Y).

Step (b2): a step in which 0.1 to 20 parts by mass of the polyamidemaster batch (Y) obtained in the step (b1) described above and 99.9 to80 parts by mass of the polyamide (X) are molten and kneaded.

In the above process, the polyamide (X) and the alkali compound (A) aremolten and kneaded by means of the extrusion equipment to obtain thepolyamide master batch (Y) containing the alkali compound (A) having ahigh concentration, and then the polyamide master batch (Y) obtained andthe polyamide (X) are blended and then molten and kneaded to obtain apolyamide resin composition. Production of gels can be inhibited in amold processing in which adding directly the alkali compound (A) to thepolyamide (X). Further, using the polyamide master batch (Y) obtained bymelting and kneading the polyamide (X) and the alkali compound (A), thealkali compound (A) can be enough dispersed in molding products, therebyobtaining the molding products having a more stable moldability and agood appearance without whitening and irregularities.

In the present invention, examples of the alkali compound (A) includehydroxides, hydrides, alkoxides, carbonates, hydrogencarbonates andcarboxylates of alkali metals and alkaline earth metals, and anhydroussalts and hydrate salts thereof can be used. Mass ratio between thepolyamide (X) and the alkali compound (A) in the polyamide master batch(Y) is calculated by reducing mass of the alkali compound (A) to ananhydrous salt equivalent mass even if the alkali compound (A) is ahydrate salt.

In the step (b1), a blend ratio (the polyamide (X)/the alkali compound(A)) of the polyamide (X) and the alkali compound (A) is preferably 90to 99 parts by mass/10 to 1 parts by mass, more preferably 92 to 99parts by mass/8 to 1 parts by mass and further preferably 94 to 98 partsby mass/6 to 2 parts by mass from the viewpoints of inhibiting areduction in the viscosity and inhibiting production of gels and burntdeposits and coloring.

In the step (b2), a blend ratio (the polyamide master batch (Y)/thepolyamide (X)) of the polyamide master batch (Y) and the polyamide (X)is preferably 0.1 to 20 parts by mass/99.9 to 80 parts by mass, morepreferably 0.5 to 20 parts by mass/99.5 to 80 parts by mass, furtherpreferably 0.5 to 10 parts by mass/99.5 to 90 parts by mass and furtherpreferably 1 to 5 parts by mass/99 to 95 parts by mass from theviewpoints of the moldability and inhibiting production of gels andburnt deposits.

In the polyamide resin composition of the present invention produced bythe process described above, gels can be inhibited from being producedin melt polymerization of the polyamide, and gels and burnt deposits canbe inhibited from being produced as well in mold processing of the resincomposition obtained.

In the present invention, an effect of inhibiting gels of the polyamideresin composition from being produced is evaluated by comparing a gelfraction of the polyamide heated at a fixed temperature for a fixed timein a molten state at a high pressure under the estimation of a state towhich the polyamide is exposed in molding. When the resin heated underpressure is dipped in hexafluoroisopropanol (HFIP) for 24 hours, theresin which is not gelatinized is completely dissolved therein, but theresin which is gelatinized remains in the form of an insoluble componentof a swollen state. The gel fraction is calculated from the aboveinsoluble component. The gel fraction referred to in the presentinvention means a value determined in terms of a percentage by dividinga mass of a residue obtained by filtrating the above insoluble componentunder vacuum by a membrane filter and then drying it by a denominatorwhich is a mass of the resin weighed in advance before dipping in HFIP.

A gel fraction of the polyamide resin composition of the presentinvention is smaller than a gel fraction of a polyamide resincomposition produced without adding the alkali compound (A) afterpolymerizing the polyamide. This shows that gels are inhibited frombeing produced in mold processing of the polyamide resin composition ofthe present invention. A gel fraction of the polyamide resin compositionof the present invention observed when it is allowed to stay for aprescribed time at 270 to 290° C. which is a resin temperature of thepolyamide resin in mold processing is preferably ½ or less, morepreferably ⅓ or less and further preferably ⅕ or less of a gel fractionobserved when the polyamide resin composition produced without addingthe alkali compound (A) is allowed to stay on the same conditions. Thestaying time can be set to, for example, 24, 36 or 72 hours.

The index that the polyamide resin composition of the present inventionhas a good appearance and good physical properties can be evaluated byan average production amount of fish eyes counted by observing a filmprepared from the polyamide resin composition under a fish eyeinspection equipment. A cause of generating fish eyes in the polyamideresin composition is considered to be attributable to flowing of gelsgenerated in the molding machine and insoluble matters precipitated fromthe polyamide resin composition. In the present invention, a countnumber of foreign matters having a circle-corresponding diameter of 20μm or more is preferably 900 pieces or less, more preferably 700 piecesor less and further preferably 600 pieces or less per m² of thepolyamide film having a thickness of 50 μm. If it exceeds 900 pieces,irregularities are visually confirmed to be present on a film surface,and the appearance is damaged. In addition thereto, breaking is likelyto be brought about in molding, and therefore it is not preferred.

The polyamide resin composition of the present invention can be blendedwith one or a plurality of other resins such as nylon 6, nylon 66, nylon66,6, polyesters, polyolefins, phenoxy resins and the like as long asthe object is not damaged. Further, capable of being added are additivesincluding inorganic fillers such as glass fibers, carbon fibers and thelike; tabular inorganic fillers such as glass flakes, talc, kaolin,mica, montmorillonite, organic clays and the like; impact resistantmodifying materials such as various elastomers and the like; crystalnucleus agents; lubricants such as fatty acid amide base lubricants,fatty acid amide base compounds and the like; antioxidants such ascopper compounds, organic or inorganic halogen base compounds, hinderedphenol base antioxidants, hindered amine base antioxidants, hydrazinebase antioxidants, sulfur base compounds, phosphorus base compounds andthe like; coloring inhibitors; UV absorbers such as benzotriazole baseUV absorbers and the like; additives such as mold releasing agents,plasticizers, coloring agents and the like; compounds containing cobaltmetal, benzoquinones, anthraquinones and naphthoquinones which arecompounds providing an oxygen scavenging ability.

The polyamide resin composition of the present invention is excellent ina gas-barrier property and a transparency and has a stable meltcharacteristic. The polyamide resin composition of the present inventioncan be processed into various shapes such as sheets, films,injection-molded bottles, blow bottles, injection-molded cups and thelike by making use of the above polyamide resin composition for at leasta part thereof to prepare molded articles. It can be used preferably forpackaging materials, packaging vessels and fiber materials.

A production method of the molded articles shall not specifically berestricted, and they can be produced by optional methods. They can beproduced by, for example, extrusion molding and injection molding. Also,the molded articles obtained by extrusion molding and injection moldingmay be further subjected to mold processing by single shaft stretching,double shaft stretching, stretching blow and the like.

To be specific, they can be processed into films and sheets by anextrusion method in which a T die is equipped, an inflation film methodand the like, and the raw material films obtained are further subjectedto stretching processing, whereby stretched films and heat shrinkablefilms can be obtained. Further, injection-molded cups can be prepared byan injection molding method, and blow bottles can be prepared by a blowmolding method. A preform is produced by injection molding, and then abottle can be prepared from it by blow molding.

Also, they can be processed as well into films and sheets having amultilayer structure with other resins, for example, polyethylene,polypropylene, nylon 6 and PET, metal foils, papers and the like bymethods such as extrusion laminate, coextrusion and the like. Theprocessed films and sheets can be used for wraps, pouches of variousshapes, cap materials for vessels, packaging vessels such as bottles,cups, trays, tubes and the like. Further, they can be processed as wellinto preforms and bottles having a multilayer structure with PET and thelike by a multilayer injection molding method.

Packaging vessels obtained by making use of the polyamide resincomposition of the present invention are excellent in a gas-barrierproperty and a transparency. The above packing vessels can be chargedwith various products including, for example, liquid beverages such ascarbonated beverages, juices, water, milk, Japanese sake, whisky,distilled spirits, coffee, tea, jelly beverages, health beverages andthe like, seasonings such as seasoning liquids, sauces, soy sauces,dressings, liquid stocks, mayonnaises, fermented soybean pastes, gratedspices and the like, paste foods such as jams, creams, chocolate pastesand the like, liquid foods represented by liquid processed foods such asliquid soups, cooked foods, pickles, stews and the like, crude noodlesand boiled noodles such as buckwheat noodles, noodles, Chinese noodlesand the like, rice before cooking such as milled rice,humidity-conditioned rice, non-washing rice and the like, cooked rice,high moisture foods represented by processed rice products such asboiled rice mixed with fishes and vegetables, festive red rice, ricegruel and the like; low moisture foods represented by powder seasoningssuch as powder soup, instant bouillon and the like, dried vegetables,coffee beans, coffee powder, tea, cakes prepared from cereals as rawmaterials; solid and liquid chemicals such as agricultural chemicals,insecticides and the like, liquid and paste drugs and medicines, skinlotions, skin creams, skin emulsions, hair dressings, hair dyes,shampoos, soaps, detergents and the like.

The polyamide resin composition of the present invention can be used asmaterials for gasoline tanks and hoses of cars, bikes and the like asgasoline-barrier materials. The polyamide resin composition of thepresent invention can be used as a fiber material for monofilaments andthe like.

[Multilayer Molded Articles]

The multilayer molded article of the present invention comprises anoutermost layer, an innermost layer and at least one gas-barrier layerbetween the outermost layer and the innermost layer, and the polyamideresin composition of the present invention is used as the gas-barrierlayer in order to prevent gels and burnt deposits from being produced inthe mold processing. The multilayer molded article of the presentinvention is preferably a multilayer bottle obtained by blow-molding amultilayer preform by a hot parison method or a cold parison method.

(Polyester Resin)

The outermost layer and the innermost layer in the multilayer moldedarticle of the present invention are constituted from a polyester resincomprising a dicarboxylic acid unit containing 80 mol % or more of aterephthalic acid unit and a diol unit containing 80 mol % or more of anethylene glycol unit. Also, the multilayer molded article of the presentinvention may have an intermediate layer if necessary, and it isconstituted preferably from the polyester resin described above. Thepolyester resin constituting the outermost layer, the innermost layerand the intermediate layer may be same of different.

The polyester resin constituting the outermost layer, the innermostlayer and the intermediate layer in the multilayer molded article of thepresent invention is a polyester resin comprising a dicarboxylic acidunit containing 80 mol % or more, preferably 90 mol % or more of aterephthalic acid unit and a diol unit containing 80 mol % or more,preferably 90 mol % or more of an ethylene glycol unit. The abovepolyester resin is obtained by subjecting a dicarboxylic acid componentcontaining 80 mol % or more, preferably 90 mol % or more of terephthalicacid and a diol component containing 80 mol % or more, preferably 90 mol% or more of ethylene glycol to polycondensation reaction.

Polyethylene terephthalate is suitably used as the polyester resin.Excellent characteristics can be exerted in all of a transparency, amechanical strength, an injection moldability and a stretching blowmoldability with which polyethylene terephthalate is provided.

Isophthalic acid, diphenyl ether-4,4-dicarboxylic acid, naphthalene-1,4-or -2,6-dicarboxylic acid, adipic acid, sebacic acid,decane-1,10-carboxylic acid and hexahydroterephthalic acid can be as thedicarboxylic acid component other than terephthalic acid. Also,propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol,cyclohexanedimethanol, 2,2-bis(4-hydroxyphenyl)propane,2,2-bis(4-hydroxyethoxyphenyl)propane and the like can be as the diolcomponent other than ethylene glycol. Further, oxyacids such asp-oxybenzoic acid and the like can also be used as a raw materialmonomer for the polyester resin.

An intrinsic viscosity of the polyester resin is preferably 0.55 to1.30, more preferably 0.65 to 1.20. If the intrinsic viscosity is 0.55or more, a multilayer preform can be obtained in a transparent amorphousstate, and the multilayer bottle obtained has a satisfactory mechanicalstrength. Further, if the intrinsic viscosity is 1.30 or less, a bottleis readily molded without damaging a fluidity in molding.

The outermost layer and the innermost layer in the multilayer moldedarticle of the present invention may contain other thermoplastic resinsand various additives as long as the characteristics of the polyesterresin are not damaged, but the polyester resin accounts preferably for90% by mass or more.

Thermoplastic polyester resins such as polyethylene2,6-naphthalenedicaboxylate and the like, polyolefin base resins,polycarbonate, polyacrylonitrile, polyvinyl chloride, polystyrene andthe like can be shown as the examples of the thermoplastic resinsdescribed above.

Further, UV absorbers, oxygen absorbers, coloring agents, IR absorbers(reheat additive) for accelerating heating of a preform to shortenrecycling time in molding and the like can be shown as the examples ofthe additives described above.

(Production Method of Multilayer Molded Article)

The multilayer molded article of the present invention, particularly themultilayer bottle is obtained by injecting a polyester resin from aninjection cylinder at a skin side and a polyamide resin from aninjection cylinder at a core side into a metal die cavity through ametal die hot runner by means of an injection molding machine equippedwith two injection cylinders to obtain a multilayer preform andsubjecting the preform obtained above to double shaft stretching blowmolding by a publicly known method. Alternatively, it is obtained byextruding a polyester resin from an extruding equipment at a skin sideand a polyamide resin from an extruding equipment at a core side in acylindrical form by means of a blow molding machine equipped with twoextruding equipments and subjecting the extruded matter intermittentlyto blow molding. Also, an adhesive layer may be provided, if necessary,between the layers.

In general, publicly known methods such as a so-called cold parisonmethod, a so-called hot parison method and the like are available as amethod for blow-molding a multilayer preform which is a precursor. Itincludes, for example, a method in which the multilayer preform isheated on a surface at 80 to 120° C. and then stretched in an axialdirection by a mechanical means such as pushing by a core rod insert andin which it is then stretched in a lateral direction and blow-molded byblowing high pressure air of usually 2 to 4 MPa and a method in whichthe multilayer preform is crystallized in a mouth part and heated on asurface at 80 to 120° C. and in which it is then blow-molded in a metaldie of 90 to 150° C.

In the present invention, a heating temperature of the preform ispreferably 90 to 110° C., more preferably 95 to 108° C. If a heatingtemperature of the preform is lower than 90° C., heating isinsufficient, and the gas-barrier layer or the PET layer iscold-stretched and whitened in a certain case. If it is higher than 110°C., the gas-barrier layer is crystallized and whitened in a certaincase. Further, the interlayer peeling resistant performance is reducedin a certain case.

In the present invention, the gas-barrier property and the moldabilityare excellent, and therefore the multilayer bottle has preferably athree layer structure of a polyester resin layer/a gas-barrier layer/apolyester resin layer or a five layer structure of a polyester resinlayer/a gas-barrier layer/a polyester resin layer/a gas-barrier layer/apolyester resin layer.

The multilayer bottle of a three layer structure or a five layerstructure is obtained by subjecting a multilayer preform of a threelayer structure or a five layer structure to double shaft stretchingblow molding by a publicly known method. A production method for themultilayer preform of a three layer structure or a five layer structureshall not specifically be restricted, and publicly known methods can beused. For example, in a step in which the polyester resin constitutingthe innermost layer and the outermost layer is injected from a skin sideinjection cylinder and in which the resin constituting the gas-barrierlayer is injected from a core side injection cylinder, the polyesterresin is first injected, and then the resin constituting the gas-barrierlayer and the polyester resin are injected at the same time; next, arequired amount of the polyester resin is injected to fulfill a metaldie cavity, whereby the multilayer preform of a three layer structure (apolyester resin layer/a gas-barrier layer/a polyester resin layer) canbe produced.

Further, in a step in which the polyester resin constituting theinnermost layer and the outermost layer is injected from a skin sideinjection cylinder and in which the resin constituting the gas-barrierlayer is injected from a core side injection cylinder, the polyesterresin is first injected, and then the resin constituting the gas-barrierlayer is injected separately; finally, the polyester resin is injectedto fulfill a metal die cavity, whereby the multilayer preform of a fivelayer structure (a polyester resin layer/a gas-barrier layer/a polyesterresin layer/a gas-barrier layer/a polyester resin layer) can beproduced.

The method for producing the multilayer preform shall not be restrictedto the methods described above.

A thickness of the polyester resin layer in the multilayer preform ispreferably 0.01 to 1.0 mm, and a thickness of the gas-barrier layer ispreferably 0.005 to 0.2 mm (5 to 200 μm). A thickness of the multilayerbottle does not have to be fixed over a whole part of the bottle andfalls usually in a range of 0.2 to 1.0 mm.

In the multilayer bottle obtained by subjecting the multilayer preformto double shaft stretching blow molding, the gas-barrier performance canbe exerted as long as the gas-barrier layer is present at least on abarrel part of the multilayer bottle, and if the gas-barrier layer isextended up to a tip vicinity of a stopper part in the multilayerbottle, the gas-barrier performance is further better.

In the multilayer molded article of the present invention, a mass of thegas-barrier layer accounts for preferably 1 to 20% by mass, morepreferably 2 to 15% by mass and particularly preferably 3 to 10% by massbased on a total mass of the multilayer bottle. Controlling a mass ofthe gas-barrier layer to the ranges described above provides amultilayer bottle having a good gas-barrier property and makes it easyto mold the multilayer preform which is a precursor into the multilayerbottle.

The multilayer molded article of the present invention provides lessburnt deposit mixed in the products. The multilayer molded article ofthe present invention is suitable for receiving and storing variousproducts including, for example, liquid beverages such as carbonatedbeverages, juices, water, milk, Japanese sake, whisky, distilledspirits, coffee, tea, jelly beverages, health beverages and the like,seasonings such as seasoning liquids, sauces, soy sauces, dressings,liquid stocks and the like, liquid foods such as liquid soups and thelike, liquid drugs and medicines, skin lotions, skin emulsions, hairdressings, hair dyes, shampoos and the like. The multilayer moldedarticle of the present invention generates less burnt deposit inproduction and prevents the burnt deposits from clogging flow channelsin an inside of a molding machine, and it can cut a labor hour formaintenance of the apparatus and contribute to stable production of themultilayer bottle and the like.

EXAMPLES

The present invention shall be explained below in further details withreference to examples, but the present invention shall not be restrictedto them.

[Measurement of Physical Properties of Polyamide and Polyamide ResinComposition]

A terminal amino group concentration and a terminal carboxyl groupconcentration in the polyamide and a total mole concentration M of analkali metal atom and an alkaline earth metal atom and a moleconcentration P of a phosphorus atom in the polyamide resin compositionwere measured by the following methods.

(1) Terminal Amino Group Concentration:

Polyamide 0.3 to 0.5 g was precisely weighed and dissolved in 30 ml of aphenol/ethanol solution (4/1 volume ratio) at 20 to 30° C. by stirring.After completely dissolved, the solution was neutralized and titrated byan N/100 hydrochloric acid aqueous solution while stirring to determinethe terminal amino group concentration.

(2) Terminal Carboxyl Group Concentration:

Polyamide 0.3 to 0.5 g was precisely weighed and dissolved in 30 ml ofbenzyl alcohol at 160 to 180° C. by stirring under nitrogen flow. Aftercompletely dissolved, the solution was cooled down to 80° C. or lowerunder nitrogen flow, and 10 ml of methanol was added thereto whilestirring. The solution was neutralized and titrated by an N/100 sodiumhydroxide aqueous solution to determine the terminal carboxyl groupconcentration.

(3) Total Mole Concentration M of an Alkali Metal Atom Concentration andan Alkaline Earth Metal Atom Concentration and a Mole Concentration P ofa Phosphorus Atom:

A total mole concentration M of an alkali metal atom and an alkalineearth metal atom and a mole concentration P of a phosphorus atom eachcontained per g of the polyamide resin composition were quantitativelydetermined by means of an atomic absorption spectrometer (trade name:AA-6650, manufactured by Shimadzu Corporation) and an ICP emissionspectrometer (trade name: ICPE-9000, manufactured by ShimadzuCorporation) after the polyamide resin composition was subjected todecomposition treatment in nitric acid by a microwave. The measuredvalues were obtained in terms of a mass ratio (ppm), and therefore M andP were calculated by using the atomic masses and the valencies.

[Evaluation of Film]

The films obtained in the example and the comparative example wereevaluated by the following methods.

(1) Fish Eye Number:

The films obtained in the example and the comparative example wereallowed to pass between a camera of a fish eye inspection equipment anda light source and reeled on a reeling equipment, and a fish eye number(circle-corresponding diameter: 20 μm or more) of the film having awidth of 10 cm, a length of 50 m and a thickness of 50 μm was countedwhen one hour passed since starting extrusion to calculate the fish eyenumber per m². The smaller the fish eye number is, the more preferable.

(2) Resin Pressure of Extrusion Equipment Head:

After finishing counting of the fish eye number, the reeling velocitywas adjusted to prepare a film having a width of 15 cm and a thicknessof 250 μm. Then, the extrusion was continued to measure the resinpressures of the extrusion equipment head respectively immediately afterstarting the extrusion, after 3 hours passed and after 6 hours passed,and the presence of a change thereof was measured. A smaller changeamount of the resin pressures of the extrusion equipment head ispreferred.

(3) Appearance of the Film:

The appearance of the films obtained was visually observed. It ispreferred that coloring and foreign matters such as gels and the likeare not observed in the films.

(4) Gel Fraction: (Preparation of Staying Sample)

The film having a thickness of 250 μm described above was cut in a formof a circle having a diameter of 30 mm, and four sheets thereof wereprepared. The above circular films were concentrically superposed andinserted into a hole part of a 100×100 mm polytetrafluoroethylene sheetof 1 mm thickness having a hole bored in a diameter of 30 mm, andfurther, the above sheet was interposed between two 100×100 mmpolytetrafluoroethylene sheets of 1 mm thickness.

Next, the foregoing polytetrafluoroethylene sheets which interposed thefilm described above therebetween were disposed in a center of thegroove in a 150×150 mm metal plate of 15 mm thickness having a 120×120mm groove of 3 mm depth in a central part, and further, it was coveredthereon with a 150×150 mm metal plate of 15 mm thickness. Then, themetal plates were fixed by a bolt.

Subsequently, the metal plates were heated on the respective conditionsof 72 hours at 270° C., 24 hours at 290° C. or 36 hours at 290° C. in astate in which the above metal plates were interposed at 50 kg/cm² ormore by a hot press equipment heated in advance. After each time passed,the above metal plates were taken out and quenched, and after they weresufficiently cooled down to room temperature, the staying sample wastaken out.

(Calculation of Gel Fraction)

Next, the staying sample described above was dried at 60° C. for 30minutes in a constant temperature dryer, and then 100 mg of the driedsample was immediately weighed. The weighed staying sample was dipped in10 ml of hexafluoroisopropanol (HFIP) having a purity of 99% for 24hours, and then it was filtrated under vacuum through a membrane filterhaving a pore diameter of 300 μm which was weighed in advance. A residueremaining on the membrane filter was washed three times by 2 ml of HFIP,and then the filter having thereon the residue was dried at 60° C. for30 minutes in a constant temperature dryer.

A total mass of the residue and the filter which were dried was weighed,and an amount (gel amount) of an HFIP-insoluble component in the stayingsample was calculated from a difference thereof from a mass of themembrane filter which was weighed in advance. The gel fraction wasdetermined in terms of % by mass of the HFIP-insoluble component in thestaying sample based on the staying sample before dipped in HFIP.

The same operation was carried out three times on the same conditionsfrom preparation of the staying sample, and an average value of the gelfraction in the respective conditions was determined.

[Evaluation of Multilayer Molded Article (Preform)]

The preforms obtained in the example and the comparative example wereevaluated by the following methods.

(1) Number of Burnt Deposits Generated:

The three layer preform (27 g) comprising a polyester resin layer/agas-barrier layer/a polyester resin layer was injection-molded in 2,500shots to obtain 10,000 sheets of the preforms. Among the preformsobtained, the number of the preforms having burnt deposits was counted.

(2) Stability of Preforms (PFM):

It was visually judged whether or not a barrier layer was stably presentin the preform. Four sheets of the preforms obtained by injection in onecycle were cut in a vertical direction, and an iodine tincture wasapplied on a cross section thereof to dye only a polyamide resincomposition layer (barrier layer), whereby it was confirmed whether ornot the present positions of the barrier layers in the four preformswere aligned. If the barrier layers are not stably present, the presentpositions of the barrier layers in a neck part of the preforms arescattered, and the quality of the resulting products is deteriorated.

(3) Weighing Time:

Measured was time required for weighing a prescribed amount of the resincomposition in a cylinder for melting and injection-molding thepolyamide resin composition in molding the preform. The too longweighing time means that the moldability is inferior.

Example 101 Melt Polymerization of Polyamide

A reaction vessel having a content volume of 50 liter equipped with astirrer, a partial condenser, a full condenser, a thermometer, adropping funnel, a nitrogen introducing tube and a strand die wascharged with 15,000 g (102.6 mole) of adipic acid precisely weighed,2,496 mg (24.49 mmol, 30 ppm in terms of a phosphorus atom concentrationin the polyamide) of sodium hypophosphite monohydrate (NaH₂PO₂.H₂O) and1,239 mg (15.10 mmol, 0.62 in terms of a mole number ratio based onsodium hypophosphite monohydrate) of sodium acetate and sufficientlysubstituted with nitrogen, and then the vessel was heated up to 170° C.while stirring an inside of the system under a small amount of nitrogenflow. Metaxylylenediamine 13,895 g (102.0 mol) was dropwise addedthereto while stirring, and an inside of the system was continuouslyheated while removing condensation water produced to an outside of thesystem. After finishing dropwise adding metaxylylenediamine, theinternal temperature was controlled to 260° C. to continue the reactionfor 40 minutes. Then, an inside of the system was pressurized bynitrogen to take out the polymer from the strand die, and this waspelletized to obtain about 24 kg of polyamide.

(Solid Phase Polymerization of Polyamide)

Next, a jacket-equipped tumble dryer in which a nitrogen gas introducingtube, a vacuum line, a vacuum pump and a thermocouple for measuring aninner temperature were provided was charged with the polyamide describedabove, and an inside of the tumble dryer was sufficiently substitutedwith nitrogen having a purity of 99% by volume or more while rotating itat a fixed speed. Then, the tumble dryer was heated under nitrogen gasflow, and the pellet temperature was elevated up to 150° C. in about 150minutes. When the pellet temperature reached 150° C., a pressure in thesystem was reduced to 1 Ton or less. The temperature was furthercontinued to be elevated, and after the pellet temperature was elevatedup to 200° C. in about 70 minutes, the system was maintained at 200° C.for 30 to 45 minutes. Then, a nitrogen gas having a purity of 99% byvolume or more was introduced into the system, and the tumble dryer wascooled while rotating to obtain polyamide (X101).

(Preparation of Polyamide Resin Composition (101))

Sodium acetate trihydrate 150 mg (75 ppm to the polyamide) was added to2 kg of the polyamide (X101) obtained and stirred and mixed to therebyprepare a polyamide resin composition (101).

(Production of Film)

Next, a film was produced by means of a 25 mmφ single shaft extrusionequipment, a film extrusion equipment comprising a head provided with afilter of 600 mesh and a T die and a receiving equipment equipped with acooling roll, a fish eye inspection equipment (model: GX70W,manufactured by Mamiya-OP Co., Ltd.) and a reeling device. The polyamideresin composition (101) was extruded in a film form from the extrusionequipment while maintaining a discharge rate of 3 kg/hour, and thereceiving velocity was adjusted to prepare a film having a width of 15cm and a thickness of 50 μm.

Example 102

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat an addition amount of metaxylylenediamine was changed to 13,916 g(102.2 mol) in preparation of the polyamide in Example 101. Then, solidphase polymerization was carried out in the same manner as in Example101 to obtain polyamide (X102).

Sodium acetate trihydrate 150 mg (75 ppm to the polyamide) was added to2 kg of the polyamide (X102) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (102), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manner as in Example 101,except that the polyamide resin composition (102) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Example 103

A polyamide resin composition (103) was prepared in the same manner asin Example 102, except that an addition amount of sodium acetatetrihydrate to the polyamide (X102) in Example 102 was changed to 200 mg(100 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manner as in Example101, except that the polyamide resin composition (103) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Example 104

A polyamide resin composition (104) was prepared in the same manner asin Example 101, except that an addition amount of sodium acetatetrihydrate to the polyamide (X101) in Example 101 was changed to 300 mg(150 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manner as in Example101, except that the polyamide resin composition (104) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Example 105

A polyamide resin composition (105) was prepared in the same manner asin Example 102, except that an addition amount of sodium acetatetrihydrate to the polyamide (X102) in Example 102 was changed to 300 mg(150 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manner as in Example101, except that the polyamide resin composition (105) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Example 106

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat in preparation of the polyamide in Example 101, an addition amountof sodium hypophosphite monohydrate was changed to 12,980 mg (122.4mmol, 150 ppm in terms of a phosphorus atom concentration in thepolyamide); an addition amount of sodium acetate was changed to 6,193 mg(75.49 mmol, 0.62 in terms of a mole number ratio based on sodiumhypophosphite monohydrate); and an addition amount ofmetaxylylenediamine was changed to 13,916 g (102.2 mol). Then, solidphase polymerization was carried out in the same manner as in Example101 to obtain polyamide (X103).

Sodium acetate trihydrate 600 mg (300 ppm to the polyamide) was added to2 kg of the polyamide (X103) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (106), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manner as in Example 101,except that the polyamide resin composition (106) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Example 107

A polyamide resin composition (107) was prepared in the same manner asin Example 106, except that an addition amount of sodium acetatetrihydrate to the polyamide (X103) in Example 106 was changed to 700 mg(350 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manner as in Example101, except that the polyamide resin composition (107) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Example 108

A polyamide resin composition (108) was prepared in the same manner asin Example 106, except that an addition amount of sodium acetatetrihydrate to the polyamide (X103) in Example 106 was changed to 1,000mg (500 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manner as in Example101, except that the polyamide resin composition (108) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Example 109

A polyamide resin composition (109) was prepared in the same manner asin Example 106, except that an addition amount of sodium acetatetrihydrate to the polyamide (X103) in Example 106 was changed to 1,600mg (800 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manner as in Example101, except that the polyamide resin composition (109) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Example 110

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat in preparation of the polyamide in Example 101, an addition amountof sodium hypophosphite monohydrate was changed to 12,980 mg (122.4mmol, 150 ppm in terms of a phosphorus atom concentration in thepolyamide); an addition amount of sodium acetate was changed to 6,193 mg(75.49 mmol, 0.62 in terms of a mole number ratio based on sodiumhypophosphite monohydrate); and an addition amount ofmetaxylylenediamine was changed to 13,874 g (101.9 mol). Then, solidphase polymerization was carried out in the same manner as in Example101 to obtain polyamide (X104).

Sodium acetate trihydrate 1,600 mg (800 ppm to the polyamide) was addedto 2 kg of the polyamide (X104) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (110), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manner as in Example 101,except that the polyamide resin composition (110) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Example 111

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat in preparation of the polyamide in Example 101, an addition amountof sodium hypophosphite monohydrate was changed to 12,980 mg (122.4mmol, 150 ppm in terms of a phosphorus atom concentration in thepolyamide); an addition amount of sodium acetate was changed to 6,193 mg(75.49 mmol, 0.62 in terms of a mole number ratio based on sodiumhypophosphite monohydrate); and an addition amount ofmetaxylylenediamine was changed to 13,853 g (101.7 mol). Then, solidphase polymerization was carried out in the same manner as in Example101 to obtain polyamide (X105).

Sodium acetate trihydrate 1,600 mg (800 ppm to the polyamide) was addedto 2 kg of the polyamide (X105) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (111), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manner as in Example 101,except that the polyamide resin composition (111) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Example 112

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat in preparation of the polyamide in Example 101, an addition amountof sodium hypophosphite monohydrate was changed to 12,980 mg (122.4mmol, 150 ppm in terms of a phosphorus atom concentration in thepolyamide); an addition amount of sodium acetate was changed to 6,193 mg(75.49 mmol, 0.62 in terms of a mole number ratio based on sodiumhypophosphite monohydrate); and an addition amount ofmetaxylylenediamine was changed to 13,958 g (102.5 mol). Then, solidphase polymerization was carried out in the same manner as in Example101 to obtain polyamide (X106).

Sodium acetate trihydrate 1,600 mg (800 ppm to the polyamide) was addedto 2 kg of the polyamide (X106) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (112), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manner as in Example 101,except that the polyamide resin composition (112) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Example 113

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat in preparation of the polyamide in Example 101, an addition amountof sodium hypophosphite monohydrate was changed to 12,980 mg (122.4mmol, 150 ppm in terms of a phosphorus atom concentration in thepolyamide); an addition amount of sodium acetate was changed to 6,193 mg(75.49 mmol, 0.62 in terms of a mole number ratio based on sodiumhypophosphite monohydrate); and an addition amount ofmetaxylylenediamine was changed to 13,937 g (102.3 mol). Then, solidphase polymerization was carried out in the same manner as in Example101 to obtain polyamide (X107).

Sodium acetate trihydrate 1,600 mg (800 ppm to the polyamide) was addedto 2 kg of the polyamide (X107) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (113), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manners as in Example 101,except that the polyamide resin composition (113) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Example 114

A polyamide resin composition (114) was prepared in the same manner asin Example 106, except that an addition amount of sodium acetatetrihydrate to the polyamide (X103) in Example 106 was changed to 1,800mg (900 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manner as in Example101, except that the polyamide resin composition (114) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Example 115

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat in preparation of the polyamide in Example 101, an addition amountof sodium hypophosphite monohydrate was changed to 15,570 mg (146.9mmol, 180 ppm in terms of a phosphorus atom concentration in thepolyamide) and that an addition amount of sodium acetate was changed to7,431 mg (90.59 mmol, 0.62 in terms of a mole number ratio based onsodium hypophosphite monohydrate). Then, solid phase polymerization wascarried out in the same manner as in Example 101 to obtain polyamide(X108).

Sodium acetate trihydrate 800 mg (400 ppm to the polyamide) was added to2 kg of the polyamide (X108) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (115), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manner as in Example 101,except that the polyamide resin composition (115) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Example 116

A polyamide resin composition (116) was prepared in the same manner asin Example 115, except that an addition amount of sodium acetatetrihydrate to the polyamide (X108) in Example 115 was changed to 2,000mg (1,000 ppm to the polyamide), and the physical properties thereofwere measured. Further, a film was produced in the same manner as inExample 101, except that the polyamide resin composition (116) was used,and it was evaluated. The results thereof are shown in Tables 1 and 2.

Example 117

Sodium acetate 400 mg (200 ppm to the polyamide) dissolved in 5 ml ofdistilled warm water was added to 2 kg of the polyamide (X103) obtainedin Example 106 and mixed by stirring to thereby prepare a polyamideresin composition (117), and the physical properties thereof weremeasured in the same manners as in Example 101. Further, a film wasproduced in the same manner as in Example 101, except that the polyamideresin composition (117) was used, and it was evaluated. The resultsthereof are shown in Tables 1 and 2.

Example 118

A polyamide resin composition (118) was prepared in the same manner asin Example 117, except that an addition amount of sodium acetate to thepolyamide (X103) in Example 117 was changed to 1,000 mg (500 ppm to thepolyamide), and the physical properties thereof were measured. Further,a film was produced in the same manner as in Example 101, except thatthe polyamide resin composition (118) was used, and it was evaluated.The results thereof are shown in Tables 1 and 2.

Example 119

Sodium carbonate decahydrate 700 mg (350 ppm to the polyamide) was addedto 2 kg of the polyamide (X103) obtained in Example 106 to therebyprepare a polyamide resin composition (119), and the physical propertiesthereof were measured in the same manners as in Example 101. Further, afilm was produced in the same manner as in Example 101, except that thepolyamide resin composition (119) was used, and it was evaluated. Theresults thereof are shown in Tables 1 and 2.

Example 120

A polyamide resin composition (120) was prepared in the same manners asin Example 119, except that an addition amount of sodium carbonatedecahydrate to the polyamide (X103) in Example 119 was changed to 1,600mg (800 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manner as in Example101, except that the polyamide resin composition (120) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Example 121

Lithium acetate dihydrate 2,000 mg (1,000 ppm to the polyamide) wasadded to 2 kg of the polyamide (X103) obtained in Example 106 and mixedby stirring to thereby prepare a polyamide resin composition (121), andthe physical properties thereof were measured in the same manner as inExample 101. Further, a film was produced in the same manner as inExample 101, except that the polyamide resin composition (121) was used,and it was evaluated. The results thereof are shown in Tables 1 and 2.

Example 122

Potassium acetate 600 mg (300 ppm to the polyamide) was added to 2 kg ofthe polyamide (X103) obtained in Example 106 and mixed by stirring tothereby prepare a polyamide resin composition (122), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manner as in Example 101,except that the polyamide resin composition (122) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 101

The physical properties of the polyamide (X102) obtained in Example 102were measured in the same manners as in Example 101. Further, a film wasproduced in the same manner as in Example 101, except that the polyamide(X102) was used and that sodium acetate trihydrate was not added, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 102

The physical properties of the polyamide (X103) obtained in Example 106were measured in the same manners as in Example 101. Further, a film wasproduced in the same manner as in Example 101, except that the polyamide(X103) was used and that sodium acetate trihydrate was not added, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 103

A polyamide resin composition (123) was prepared in the same manners asin Example 102, except that an addition amount of sodium acetatetrihydrate to the polyamide (X102) in Example 102 was changed to 50 mg(25 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manners as in Example101, except that the polyamide resin composition (123) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 104

A polyamide resin composition (124) was prepared in the same manner asin Example 106, except that an addition amount of sodium acetatetrihydrate to the polyamide (X103) in Example 106 was changed to 300 mg(150 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manner as in Example101, except that the polyamide resin composition (124) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 105

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat in preparation of the polyamide in Example 101, an addition amountof metaxylylenediamine was changed to 13,972 g (102.6 mol). Then, solidphase polymerization was carried out in the same manner as in Example101 to obtain polyamide (X109).

Sodium acetate trihydrate 300 mg (150 ppm to the polyamide) was added to2 kg of the polyamide (X109) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (125), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manner as in Example 101,except that the polyamide resin composition (125) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 106

Melt polymerization and pelletization were carried out in the samemanners as in Example 11 to obtain about 24 kg of polyamide, except thatin preparation of the polyamide in Example 101, an addition amount ofmetaxylylenediamine was changed to 13,839 g (101.6 mol). Then, solidphase polymerization was carried out in the same manner as in Example101 to obtain polyamide (X110).

Sodium acetate trihydrate 300 mg (150 ppm to the polyamide) was added to2 kg of the polyamide (X110) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (126), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manners as in Example 101,except that the polyamide resin composition (126) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 107

A polyamide resin composition (127) was prepared in the same manners asin Example 102, except that an addition amount of sodium acetatetrihydrate to the polyamide (X102) in Example 102 was changed to 700 mg(350 ppm to the polyamide), and the physical properties thereof weremeasured. Further, a film was produced in the same manner as in Example101, except that the polyamide resin composition (127) was used, and itwas evaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 108

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat in preparation of the polyamide in Example 101, an addition amountof sodium hypophosphite monohydrate was changed to 12,980 mg (122.4mmol, 150 ppm in terms of a phosphorus atom concentration in thepolyamide); an addition amount of sodium acetate was changed to 6,193 mg(75.49 mmol, 0.62 in terms of a mole number ratio based on sodiumhypophosphite monohydrate); and an addition amount ofmetaxylylenediamine was changed to 13,972 g (102.6 mol). Then, solidphase polymerization was carried out in the same manner as in Example 1to obtain polyamide (X111).

Sodium acetate trihydrate 1,600 mg (800 ppm to the polyamide) was addedto 2 kg of the polyamide (X111) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (128), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manners as in Example 101,except that the polyamide resin composition (128) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 109

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat in preparation of the polyamide in Example 101, an addition amountof sodium hypophosphite monohydrate was changed to 12,980 mg (122.4mmol, 150 ppm in terms of a phosphorus atom concentration in thepolyamide); an addition amount of sodium acetate was changed to 6,193 mg(75.49 mmol, 0.62 in terms of a mole number ratio based on sodiumhypophosphite monohydrate); and an addition amount ofmetaxylylenediamine was changed to 13,839 g (101.6 mol). Then, solidphase polymerization was carried out in the same manner as in Example101 to obtain polyamide (X112).

Sodium acetate trihydrate 1,600 mg (800 ppm to the polyamide) was addedto 2 kg of the polyamide (X112) obtained above and mixed by stirring tothereby prepare a polyamide resin composition (129), and the physicalproperties thereof were measured in the same manners as in Example 101.Further, a film was produced in the same manners as in Example 101,except that the polyamide resin composition (129) was used, and it wasevaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 110

Melt polymerization and pelletization were carried out in the samemanners as in Example 101 to obtain about 24 kg of polyamide, exceptthat in preparation of the polyamide in Example 101, an addition amountof sodium hypophosphite monohydrate was changed to 21,630 mg (204.1mmol, 250 ppm in terms of a phosphorus atom concentration in thepolyamide); an addition amount of sodium acetate was changed to 10,320mg (125.8 mmol, 0.62 in terms of a mole number ratio based on sodiumhypophosphite monohydrate); and an addition amount ofmetaxylylenediamine was changed to 13,916 g (102.2 mol). Then, solidphase polymerization was carried out in the same manner as in Example101 to obtain polyamide (X113).

Sodium acetate trihydrate 3,000 mg (1,500 ppm to the polyamide) wasadded to 2 kg of the polyamide (X113) obtained above and mixed bystirring to thereby prepare a polyamide resin composition (130), and thephysical properties thereof were measured in the same manners as inExample 101. Further, a film was produced in the same manners as inExample 101, except that the polyamide resin composition (130) was used,and it was evaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 111

A polyamide resin composition (131) was prepared in the same manners asin Example 106, except that an addition amount of sodium acetatetrihydrate to the polyamide (X103) in Example 106 was changed to 3,000mg (1,500 ppm to the polyamide), and the physical properties thereofwere measured. Further, a film was produced in the same manners as inExample 101, except that the polyamide resin composition (131) was used,and it was evaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 112

Sodium acetate 200 mg (100 ppm to the polyamide) dissolved in 5 ml ofdistilled warm water was added to 2 kg of the polyamide (X103) obtainedin Example 106 and mixed by stirring to thereby prepare a polyamideresin composition (132), and the physical properties thereof weremeasured in the same manner as in Example 101. Further, a film wasproduced in the same manners as in Example 101, except that thepolyamide resin composition (132) was used, and it was evaluated. Theresults thereof are shown in Tables 1 and 2.

Comparative Example 113

A polyamide resin composition (133) was prepared in the same manners asin Comparative Example 112, except that an addition amount of sodiumacetate trihydrate to the polyamide (X103) in Comparative Example 112was changed to 1,600 mg (800 ppm to the polyamide), and the physicalproperties thereof were measured. Further, a film was produced in thesame manner as in Example 101, except that the polyamide resincomposition (133) was used, and it was evaluated. The results thereofare shown in Tables 1 and 2.

Comparative Example 114

Sodium carbonate decahydrate 400 mg (200 ppm to the polyamide) was addedto 2 kg of the polyamide (X103) obtained in Example 106 and mixed bystirring to thereby prepare a polyamide resin composition (134), and thephysical properties thereof were measured in the same manners as inExample 101. Further, a film was produced in the same manner as inExample 101, except that the polyamide resin composition (134) was used,and it was evaluated. The results thereof are shown in Tables 1 and 2.

Comparative Example 115

A polyamide resin composition (135) was prepared in the same manner asin Comparative Example 114, except that an addition amount of sodiumcarbonate decahydrate to the polyamide (X103) in Comparative Example 115was changed to 3,000 mg (1,500 ppm to the polyamide), and the physicalproperties thereof were measured. Further, a film was produced in thesame manner as in Example 101, except that the polyamide resincomposition (135) was used, and it was evaluated. The results thereofare shown in Tables 1 and 2.

Example 123

A double shaft extruding equipment (model: TEM37BS, bore diameter: 37mmφ, manufactured by Toshiba Machine Co., Ltd.) equipped with a stranddie was used to supply the polyamide (X103) obtained in Example 106 at adischarge velocity of 28.8 kg/hour and sodium acetate trihydrate at adischarge velocity of 1.2 kg/hour respectively by different feeders toturn the polyamide into a strand form. Next, it was cooled in awater-cooled bath and then pelletized by means of a pelletizer.Thereafter, the pellets were dried at 0.1 Torr or less and 140° C. for 8hours to obtain polyamide master batch (Y101).

The polyamide (X103) 1,980.0 g and the polyamide master batch (Y101)20.0 g were mixed to thereby prepare a polyamide resin composition(136), and the physical properties thereof were measured in the samemanners as in Example 101. Further, a film was produced in the samemanners as in Example 101, except that the polyamide resin composition(136) was used, and it was evaluated. The results thereof are shown inTables 3 and 4.

Example 124

A polyamide resin composition (137) was prepared in the same manners asin Comparative Example 123, except that the blend amounts of thepolyamide (X103) and the polyamide master batch (Y101) in Example 123were changed to 1,970.0 g of the polyamide (X103) and 30.0 g of thepolyamide master batch (Y101) respectively, and the physical propertiesthereof were measured. Further, a film was produced in the same manneras in Example 101, except that the polyamide resin composition (137) wasused, and it was evaluated. The results thereof are shown in Tables 3and 4.

Example 125

A polyamide resin composition (138) was prepared in the same manners asin Comparative Example 123, except that the blend amounts of thepolyamide (X103) and the polyamide master batch (Y101) in Example 123were changed to 1,960.0 g of the polyamide (X103) and 40.0 g of thepolyamide master batch (Y101) respectively, and the physical propertiesthereof were measured. Further, a film was produced in the same mannersas in Example 101, except that the polyamide resin composition (138) wasused, and it was evaluated. The results thereof are shown in Tables 3and 4.

Abbreviated expressions in Tables show the followings.

-   AcNa: Sodium acetate-   AcNa.3H₂O: Sodium acetate trihydrate-   Na₂CO₃.10H₂O: Sodium carbonate decahydrate-   AcLi.2H₂O: Lithium acetate dihydrate-   AcK: Potassium acetate

TABLE 1 Alkali compound (A) [COOH]—[NH₂] P M [ppm] (*) [μeq/g] [μmol/g][μmol/g] M/P Example 101 AcNa•3H₂O 75 42.6 0.97 2.15 2.2 Example 102AcNa•3H₂O 75 50.1 0.97 2.04 2.1 Example 103 AcNa•3H₂O 100 50.1 0.97 2.302.4 Example 104 AcNa•3H₂O 150 42.6 0.97 2.61 2.7 Example 105 AcNa•3H₂O150 50.1 0.97 2.66 2.7 Example 106 AcNa•3H₂O 300 45.7 4.84 10.01 2.1Example 107 AcNa•3H₂O 350 45.7 4.84 10.19 2.1 Example 108 AcNa•3H₂O 50045.7 4.84 11.48 2.4 Example 109 AcNa•3H₂O 800 45.7 4.84 13.60 2.8Example 110 AcNa•3H₂O 800 64.5 4.84 13.33 2.8 Example 111 AcNa•3H₂O 80073.0 4.84 13.20 2.7 Example 112 AcNa•3H₂O 800 15.5 4.84 13.27 2.7Example 113 AcNa•3H₂O 800 22.1 4.84 13.54 2.8 Example 114 AcNa•3H₂O 90045.7 4.84 14.39 3.0 Example 115 AcNa•3H₂O 400 49.3 5.81 12.23 2.1Example 116 AcNa•3H₂O 1000 49.3 5.81 16.50 2.8 Example 117 AcNa 200 45.74.84 10.09 2.1 Example 118 AcNa 500 45.7 4.84 13.65 2.8 Example 119Na₂CO₃•10H₂O 350 45.7 4.84 10.01 2.1 Example 120 Na₂CO₃•10H₂O 800 45.74.84 13.30 2.7 Example 121 AcLi•2H₂O 1000 45.7 4.84 12.84 2.7 Example122 AcK 300 45.7 4.84 13.30 2.7 Comparative Not added — 50.1 0.97 1.561.6 Example 101 Comparative Not added — 45.7 4.84 7.80 1.6 Example 102Comparative AcNa•3H₂O 25 50.1 0.97 1.69 1.7 Example 103 ComparativeAcNa•3H₂O 150 45.7 4.84 8.78 1.8 Example 104 Comparative AcNa•3H₂O 1509.7 0.97 2.54 2.6 Example 105 Comparative AcNa•3H₂O 150 80.8 0.97 2.602.7 Example 106 Comparative AcNa•3H₂O 350 50.1 0.97 4.00 4.1 Example 107Comparative AcNa•3H₂O 800 7.4 4.84 13.22 2.7 Example 108 ComparativeAcNa•3H₂O 800 89.1 4.84 13.48 2.8 Example 109 Comparative AcNa•3H₂O 150055.2 8.07 23.79 2.9 Example 110 Comparative AcNa•3H₂O 1500 45.7 4.8418.65 3.9 Example 111 Comparative AcNa 100 45.7 4.84 8.88 1.8 Example112 Comparative AcNa 800 45.7 4.84 17.09 3.5 Example 113 ComparativeNa₂CO₃•10H₂O 200 45.7 4.84 9.04 1.9 Example 114 Comparative Na₂CO₃•10H₂O1500 45.7 4.84 18.11 3.7 Example 115 (*) Concentration of the alkalicompound (A) to the polyamide P: Mole concentration of a phosphorus atomcontained per 1 gram of the polyamide resin composition M: Total moleconcentration of an alkali metal atom and an alkaline earth metal atomeach contained per 1 gram of the polyamide resin composition

TABLE 2 Resin pressure average Fish eye Gel fraction [%] value [MPa]number 270° C. 290° C. 290° C. Immediately of film Appearance 72 hr 24hr 36 hr after starting 3 hr 6 hr [/m²] of film stay stay stay Example101 2.2 2.2 2.2 300 Good 13.1 15.1 23.9 Example 102 2.2 2.2 2.2 350 Good13.6 14.1 22.7 Example 103 2.0 2.0 2.0 320 Good 8.2 8.9 12.9 Example 1042.0 2.0 2.0 310 Good 5.5 6.7 10.2 Example 105 2.0 2.0 2.0 360 Good 5.06.1 9.6 Example 106 2.0 2.0 2.0 420 Good 16.6 17.2 26.2 Example 107 2.02.0 2.0 350 Good 12.9 15.0 24.6 Example 108 1.9 1.9 1.9 360 Good 1.2 0.92.1 Example 109 1.9 1.9 1.9 620 Good 1.1 1.2 2.4 Example 110 1.9 1.9 2.0710 Good 3.3 3.2 6.8 Example 111 1.9 2.0 2.0 880 Good 7.4 7.9 12.4Example 112 1.9 1.9 2.0 800 Good 15.1 14.2 19.6 Example 113 1.9 1.9 2.0720 Good 8.1 9.1 14.1 Example 114 1.9 1.9 2.0 770 Good 0.5 0.9 4.4Example 115 2.0 2.0 2.0 500 Good 7.2 8.8 13.3 Example 116 1.8 1.9 1.9680 Good 1.2 0.7 1.2 Example 117 2.0 2.0 2.0 390 Good 10.4 12.2 20.1Example 118 1.9 1.9 1.9 650 Good 0.6 1.4 2.9 Example 119 2.0 2.0 2.0 440Good 11.1 13.1 21.1 Example 120 1.9 1.8 1.8 660 Good 0.5 0.5 0.5 Example121 1.8 1.8 1.8 600 Good 10.9 12.7 16.5 Example 122 1.9 1.9 1.9 430 Good3.4 1.9 5.5 Comparative 2.3 2.3 2.3 320 Good 31.0 35.5 55.1 Example 101Comparative 2.3 2.3 2.3 320 Good 32.9 36.2 54.3 Example 102 Comparative2.3 2.3 2.3 320 Good 25.2 25.1 39.9 Example 103 Comparative 2.0 2.0 2.1350 Good 20.3 19.9 30.1 Example 104 Comparative 2.0 2.0 2.0 790Yellowish 25.6 26.1 36.9 Example 105 Comparative 2.0 2.0 2.0 1210Irregularities 9.2 8.9 15.5 Example 106 Comparative 2.0 2.0 2.0 480Yellowish 20.9 21.4 30.0 Example 107 Comparative 1.9 1.9 2.0 1250Yellowish, 13.7 15.1 18.4 Example 108 irregularities Comparative 1.9 1.92.0 1900 Irregularities 18.8 19.2 29.1 Example 109 Comparative 1.8 2.32.7 940 Irregularities 0.9 1.1 4.3 Example 110 Comparative 1.9 2.0 2.01080 Irregularities 0.4 1.7 3.5 Example 111 Comparative 2.0 2.0 2.0 330Good 23.9 22.2 36.2 Example 112 Comparative 1.8 1.8 1.8 920Irregularities 1.2 2.3 6.6 Example 113 Comparative 2.0 2.0 2.0 400 Good20.9 21.2 30.8 Example 114 Comparative 1.9 1.9 1.9 1040 Irregularities0.3 1.4 2.2 Example 115

TABLE 3 Mass ratio of Mass ratio of Alkali polyamide (X)/ master batch(Y)/ compound [COOH]—[NH₂] alkali compound (A) polyamide (X) P M (A)[μeq/g] in master batch (Y) in resin composition [μmol/g] [μmol/g] M/PExample 123 AcNa•3H₂O 45.7 96/4 99.0/1.0 4.84 10.66 2.2 Example 124AcNa•3H₂O 45.7 96/4 98.5/1.5 4.84 12.10 2.5 Example 125 AcNa•3H₂O 45.796/4 98.0/2.0 4.84 13.51 2.8 P: Mole concentration of a phosphorus atomcontained per 1 gram of the polyamide resin composition M: Total moleconcentration of an alkali metal atom and an alkaline earth metal atomeach contained per 1 gram of the polyamide resin composition

TABLE 4 Resin pressure average Fish eye Gel fraction [%] value [MPa]number 270° C. 290° C. 290° C. Immediately of film Appearance 72 hr 24hr 36 hr after starting 3 hr 6 hr [/m²] of film stay stay stay Example123 2.1 2.1 2.1 360 Good 11.9 13.9 20.1 Example 124 2.0 2.0 2.0 360 Good1.4 2.9 6.7 Example 125 1.9 1.9 1.9 530 Good 0.5 0.6 3.3

In Comparative Examples 101 and 102 in which the alkali compound (A) wasnot added after producing the polyamide, a fish eye number of the filmswas small at first, but the gel fraction was high, and gels wereproduced when the excessive thermal history was applied by staying.

In contrast with this, the polyamide resin compositions of the presentinvention having 10 to 80 of a difference ([COOH]—[NH₂]) of a terminalcarboxyl group concentration from a terminal amino group concentrationin the polyamide, 0.32 μmol/g or more and less than 6.46 μmol/g of amole concentration P of a phosphorus atom contained per g of thepolyamide resin composition, 0.50 μmol/g or more and less than 17.00mmol/g of a total mole concentration M of an alkali metal atom and analkaline earth metal atom each contained per g of the polyamide resincomposition and 2 to 3 of M/P have a good color tone and are reduced ina fish eye number in the film, and they have a low gel fraction andproduce less gel in mold processing.

On the other hand, the polyamide resin compositions prepared inComparative Examples 103 to 115 in which the values of a difference([COOH]—[NH₂]) of a terminal carboxyl group concentration from aterminal amino group concentration in the polyamide, a moleconcentration P of a phosphorus atom contained, a total moleconcentration M of an alkali metal atom and an alkaline earth metal atomand M/P deviated from the ranges described above brought about theproblems of an inferior appearance of the films and production of gels.

Production Example 201 Production of Polyamide (X201)

A reaction vessel having a content volume of 50 liter equipped with astirrer, a partial condenser, a full condenser, a thermometer, adropping funnel, a nitrogen introducing tube and a strand die wascharged with 15,000 g (102.6 mole) of adipic acid precisely weighed,12.977 g (0.122 mol, 150 ppm in terms of a phosphorus atom concentrationin the polyamide) of sodium hypophosphite monohydrate (NaH₂PO₂.H₂O) and7.0303 g (0.0857 mol, 0.70 in terms of a mole number ratio based onsodium hypophosphite monohydrate) of sodium acetate and sufficientlysubstituted with nitrogen, and then the vessel was heated up to 170° C.while stirring an inside of the system under a small amount of nitrogenflow. Metaxylylenediamine 13,928 g (102.26 mol) was dropwise addedthereto while stirring, and an inside of the system was continuouslyheated while removing condensation water produced to an outside of thesystem. After finishing dropwise adding metaxylylenediamine, theinternal temperature was controlled to 260° C. to continue the reactionfor 40 minutes. Then, an inside of the system was pressurized bynitrogen to take out the polymer from the strand die, and this waspelletized to obtain about 24 kg of polyamide.

Next, a jacket-equipped tumble dryer in which a nitrogen gas introducingtube, a vacuum line, a vacuum pump and a thermocouple for measuring aninner temperature were provided was charged with the polyamide describedabove, and an inside of the tumble dryer was sufficiently substitutedwith nitrogen having a purity of 99% by volume or more while rotating itat a fixed speed. Then, the tumble dryer was heated under nitrogen gasflow, and the pellet temperature was elevated up to 150° C. in about 150minutes. When the pellet temperature reached 150° C., a pressure in thesystem was reduced to 1 Torr or less. The temperature was furthercontinued to be elevated, and after the pellet temperature was elevatedup to 200° C. in about 70 minutes, the system was maintained at 200° C.for 30 to 45 minutes. Then, a nitrogen gas having a purity of 99% byvolume or more was introduced into the system, and the tumble dryer wascooled while rotating to obtain polyamide (X201).

Production Examples 202 to 221 Production of Polyamides (X202) to (X221)

Polyamides (X202) to (X221) were synthesized in the same manners as inProduction Example 201, except that the amounts of metaxylylenediamine,sodium hypophosphite monohydrate and sodium acetate were changed toamounts shown in Table 5. In Example 213, the amidation reaction in thepolymerization was slow, and it was difficult to carry out thepolymerization, so that polyamide (X213) could not be obtained.

The required amounts of polyamide resins necessary for the followingexamples and comparative examples were secured by repeating the sameproduction.

Production Example 222 Production of Polyamide Master Batch (Y201)

The polyamide (X214) 4,960 g and sodium acetate trihydrate 66.36 g(anhydride equivalent to 40 g) were molten and kneaded at 260° C. bymeans of a double shaft extruding equipment (model: TEM37B, manufacturedby Toshiba Machine Co., Ltd.) to obtain a polyamide master batch (Y201).Hydrated moisture of sodium acetate trihydrate was removed in themelt-kneading by vacuum ventilation.

Production Examples 223 to 228 Production Polyamide Master Batches(Y202) to (Y207)

Polyamide master batches (Y202) to (Y207) were obtained in the samemanners as in Production Example 222, except that the polyamide (X) andsodium acetate trihydrate were used in kinds and blend amounts shown inTable 6.

TABLE 5 In polyamide (X) MXDA (B) (C) (C)/(B) [COOH]—[NH₂] P atom Nametal Production Polyamide drop amount add amount add amount mole inpolyamide (X) concentration concentration Example (X) [g] [g] [g] ratio[μeq/g] [ppm] [μmol/g] 201 X201 13928 12.977 7.030 0.7 30 150 8.233 202X202 13895 13.842 7.499 0.7 50 160 8.782 203 X203 13895 15.572 8.436 0.750 180 9.879 204 X204 13895 0.865 0.469 0.7 50 10 0.549 205 X205 138951.471 0.797 0.7 50 17 0.933 206 X206 13895 1.817 0.984 0.7 50 21 1.153207 X207 13945 8.651 4.687 0.7 20 100 5.489 208 X208 13945 17.302 9.3740.7 20 200 10.977 209 X209 13945 14.707 5.691 0.5 20 170 8.233 210 X21013945 14.707 6.829 0.6 20 170 8.782 211 X211 13868 15.572 10.847 0.9 65180 11.042 212 X212 13868 15.572 12.052 1.0 65 180 11.623 213 X213 1386815.572 14.462 1.2 Not evaluated due to difficulty of polymerization 214X214 13868 13.409 6.746 0.65 65 155 8.257 215 X215 13955 17.302 8.7040.65 15 200 10.654 216 X216 13955 13.409 6.746 0.65 15 155 8.257 217X217 13851 2.595 1.306 0.65 75 30 1.598 218 X218 13851 13.409 6.746 0.6575 155 8.257 219 X219 13851 12.977 6.528 0.65 75 150 7.991 220 X22013851 13.842 6.963 0.65 75 160 8.523 221 X221 13971 13.842 6.963 0.65 5160 8.523 MXDA: metaxylylenediamine (B): phosphorus atom-containingcompound (NaH₂PO₂•H₂O) (C): alkali metal compound (CH₃COONa)

TABLE 6 Composition In master batch (Y) Polyamide (X) Alkai compound (A)¹⁾ Mass ratio of Master Add Add AcNa- polyamide (X)/ Na metal P atombatch amount amount equivalent alkali compound concentrationconcentration (Y) Kind [g] Kind [g] mass [g] (A) ²⁾ [μmol/g] [ppm] Y201X214 4960 AcNa•3H₂O 66.36 40 99.2/0.8 105.7 4.964 Y202 X214 4910AcNa•3H₂O 149.30 90 98.2/1.8 227.5 4.914 Y203 X215 4900 AcNa•3H₂O 165.89100 98.0/2.0 254.3 6.328 Y204 X216 4950 AcNa•3H₂O 82.95 50 99.0/1.0130.1 4.954 Y205 X216 4600 AcNa•3H₂O 663.56 400 92.0/8.0 982.8 4.604Y206 X217 4500 AcNa•3H₂O 829.45 500  90.0/10.0 1220.5 0.872 Y207 X2184800 AcNa•3H₂O 331.78 200 96.0/4.0 495.6 4.804 ¹⁾ Mass of alkalicompound (A) was calculated as an anhydrous salt equivalent mass, whenalkali compound (A) is a hydrate salt. ²⁾ Mass ratio of alkali compound(A) in master batch (Y) was calculated by reducing mass of alkalicompound (A) to an anhydrous salt equivalent mass, when alkali compound(A) is a hydrate salt.

Example 201

Sodium acetate 3.0 g was added to 20 kg of the polyamide (X201), and themixture was stirred and mixed to obtain a polyamide resin composition.The polyamide resin composition thus obtained was used to produce athree layer preform comprising a polyester layer/a barrier layer/apolyester layer.

Polyethylene terephthalate (trade name: RT543C, manufactured by JapanUnipet Co., Ltd.) having an intrinsic viscosity of 0.75 (measured at 30°C. in a mixed solvent of phenol/tetrachloroethane=6/4 (mass ratio)) wasused for the polyester layer, and a polyamide resin compositiondescribed in Table 7 was used for the gas-barrier layer.

The three layer preform has a shape of a whole length: 95 mm, a majordiameter: 22 mm and a wall thickness: 4.2 mm, and it was produced bymeans of an injection molding machine (model: M200, manufactured byMeiki Co., Ltd.) having two injection cylinders and a metal die (fourarticles molded per shot, manufactured by Kata Systems Company).

The molding conditions of the three layer preform are shown below, andin order to accelerate degradation of the resin, an injection cylindertemperature at a core side (barrier layer side) and a resin flow channeltemperature in an inside of the metal die were set to higher levels thanusual.

Injection cylinder temperature at a skin side: 280° C.

Injection cylinder temperature at a core side: 290° C.

Resin flow channel temperature in an inside of the metal die: 290° C.

Die metal cooling water temperature: 15° C.

Proportion of the barrier resin in the preform: 5% by mass

Cycle time: 40 seconds

Examples 202 to 215

Multilayer preforms were produced in the same manners as in Example 201,except that the polyamide (X) and sodium acetate were used in kinds andblend amounts shown in Table 7.

Example 216

The polyamide (X211) 19.5 kg and the polyamide master batch (Y201) 0.5kg were stirred and mixed to obtain a polyamide resin composition. Thepolyamide resin composition thus obtained was used to produce amultilayer preform.

Examples 217 to 223

Multilayer preforms were produced in the same manners as in Example 216,except that the polyamide master batches (Y) were used in kinds andblend amounts shown in Table 7.

Comparative Example 201

A preform was planned to be produced by using the polyamide (X213) asthe polyamide (X), but the polyamide (X213) could not be obtained inProduction Example 213 and therefore was given up.

Comparative Examples 202 to 204

Multilayer preforms were produced in the same manners as in Example 201,except that the polyamide (X) and sodium acetate were used in kinds andblend amounts shown in Table 7.

The preforms produced in Comparative Example 202 and Comparative Example204 had a good stability but generated a lot of burnt deposits. InComparative Example 203, the weighing time in the injection molding waslong, and the present positions of the barrier layer in the preform werescattered. The stable preform could not be obtained, and therefore theburnt deposits were not evaluated.

TABLE 7 Mass ratio Properties of Composition of of master polyamideresin composition Evaluation of preform polyamide resin compositionbatch (Y)/ Na metal P atom Number of Polyamide Master polyamideConcentration Concentration M/P preform Weighing (X) AcNa batch (Y) (X)in resin M P mole having burnt PFM time Kind [g] [g] Kind [g]composition [μmol/g] [μmol/g] [ppm] ratio deposits stability [sec]Example 201 X201 20000 3 — 0 — 10.06 4.84 149.98 2.1 1 good 5 Example202 X201 20000 6 — 0 — 11.89 4.84 149.96 2.5 0 good 6 Example 203 X20120000 6.6 — 0 — 12.25 4.84 149.95 2.5 1 good 6 Example 204 X201 2000010.3 — 0 — 14.50 4.84 149.92 3.0 4 good 8 Example 205 X202 20000 11 — 0— 15.48 5.16 159.91 3.0 5 good 10 Example 206 X203 20000 11.5 — 0 —16.88 5.81 179.90 2.9 6 good 12 Example 207 X204 20000 0.5 — 0 — 0.850.32 10.00 2.7 5 good 4 Example 208 X205 20000 0.5 — 0 — 1.24 0.55 17.002.3 3 good 4 Example 209 X206 20000 1.3 — 0 — 1.94 0.68 21.00 2.9 3 good4 Example 210 X207 20000 6.8 — 0 — 9.63 3.23 99.97 3.0 1 good 6 Example211 X208 20000 9.8 — 0 — 16.94 6.45 199.90 2.6 5 good 7 Example 212 X20920000 12 — 0 — 15.54 5.49 169.90 2.8 5 good 12 Example 213 X210 20000 12— 0 — 16.09 5.49 169.90 2.9 6 good 12 Example 214 X211 20000 9 — 0 —16.52 5.81 179.92 2.8 5 good 7 Example 215 X212 20000 8.5 — 0 — 16.805.81 179.92 2.9 5 good 6 Example 216 X211 19500 0 Y201 500 2.5/97.510.69 5.00 154.97 2.1 1 good 4 Example 217 X211 19800 0 Y202 200 1/9910.45 5.00 154.97 2.1 2 good 4 Example 218 X211 19600 0 Y203 400 2/9815.53 6.45 199.92 2.4 5 good 4 Example 219 X211 19000 0 Y204 1000 5/9514.35 5.00 154.92 2.9 3 good 4 Example 220 X211 19900 0 Y205 1000.5/99.5 13.13 5.00 154.94 2.6 1 good 4 Example 221 X211 19980 0 Y206 200.1/99.9 2.82 0.97 30.00 2.9 1 good 4 Example 222 X211 19750 0 Y207 2501.25/98.75 14.35 5.00 154.92 2.9 5 good 4 Example 223 X211 19920 0 Y20780 0.4/99.6 10.21 5.00 154.98 2.0 2 good 4 Comparative X213 20000 0 — 0— — — — — Not evaluated due to difficulty Example 201 of polymerizationComparative X219 20000 0 — 0 — 7.99 4.84 150.00 1.7 20 good 4 Example202 Comparative X220 20000 20 — 0 — 20.69 5.17 160.00 4.0 — Disturbed 30Example 203 Comparative X221 20000 10 — 0 — 14.61 5.17 160.00 2.8 21good 8 Example 204

As apparent from the results obtained in the examples and thecomparative examples, the multilayer molded articles of the presentinvention provided less burnt deposit and had a good productivity.

INDUSTRIAL APPLICABILITY

The polyamide resin composition of the present invention is excellent ina gas-barrier property and a transparency and has a good color tone, andin addition thereto, it has less number of fish eyes in the film and alow gel fraction and produces less gel in mold processing. Accordingly,the polyamide resin composition of the present invention is industriallyuseful as a packaging material, a gasoline-barrier material, a fibermaterial and the like. Also, the multilayer molded article of thepresent invention provides less burnt deposit and has a very highindustrial value as a multilayer bottle and the like.

1. A polyamide resin composition; comprising: a polyamide (X) comprisinga diamine unit comprising 70 mol % or more of a metaxylylenediamine unitand a dicarboxylic acid unit; and an alkali compound (A), whereinequations (1) to (4) are satisfied:10≦([COOH]—[NH₂])≦80  (1)0 32≦P<6.46  (2)0.50<M<17.00  (3)2≦M/P≦3  (4) wherein [COOH] is a concentration (μeq/g) of a terminalcarboxyl group in the polyamide (X); [NH₂] is a concentration (μeq/g) ofa terminal amino group in the polyamide (X); P is a mole concentration(μmol/g) of a phosphorus atom contained per gram of the polyamide resincomposition; and M is a sum (μmol/g) of values obtained by multiplying amole concentration of an alkali metal atom and a mole concentration ofan alkaline earth metal atom each contained per gram of the polyamideresin composition by valencies thereof, respectively.
 2. The polyamideresin composition of claim 1, wherein the alkali compound (A) is acarboxylate comprising 10 or less carbon atoms of an alkali metal. 3.The polyamide resin composition of claim 1, wherein the polyamide (X) isa polyamide comprising a diamine unit comprising 70 mol % or more of ametaxylylenediamine unit and a dicarboxylic acid unit comprising 70 mol% or more of an adipic acid unit.
 4. The polyamide resin composition ofclaim 1, wherein the polyamide (X) is a polyamide comprising a diamineunit comprising 70 mol % or more of a metaxylylenediamine unit and adicarboxylic acid unit comprising 70 to 99 mol % of an adipic acid unitand 1 to 30 mol % of an isophthalic acid unit.
 5. The polyamide resincomposition of claim 1, wherein the polyamide (X) is a polyamidecomprising a diamine unit comprising 70 mol % or more of ametaxylylenediamine unit and a dicarboxylic acid unit comprising 70 mol% or more of a sebacic acid unit.
 6. A process for producing thepolyamide resin composition of claim 1, the process comprising: (a)polycondensating a diamine comprising 70 mol % or more ofmetaxylylenediamine and dicarboxylic acid in the presence of aphosphorus atom-comprising compound (B), to obtain the polyamide (X);and (b) adding the alkali compound (A) to the polyamide (X).
 7. Theprocess of claim 6, wherein, in (a), the polycondensation is carried outin the presence of the phosphorus atom-comprising compound (B) and analkali metal compound (C).
 8. The process of claim 6, wherein the adding(b) comprises: (b1) melting and kneading 90 to 99 parts by mass of thepolyamide (X) and 10 to 1 part by mass of the alkali compound (A) withan extrusion equipment to obtain a polyamide master batch (Y); andmelting and kneading 0.1 to 20 parts by mass of the polyamide masterbatch (Y) and 99.9 to 80 parts by mass of the polyamide (X).
 9. Amultilayer molded article comprising: an outermost layer; an innermostlayer; and a gas-barrier layer between the outermost layer and theinnermost layer, wherein the outermost layer and the innermost layercomprise a polyester resin comprising a dicarboxylic acid unitcomprising 80 mol % or more of a terephthalic acid unit and a diol unitcomprising 80 mol % or more of an ethylene glycol unit, and thegas-barrier layer comprises the polyamide resin composition of claim 1.10. The multilayer molded article of claim 9, which is a multilayerbottle obtained by blow-molding a multilayer preform by a hot parisonmethod or a cold parison method.
 11. The polyamide resin composition ofclaim 1, wherein the polyamide (X) comprises 80 mol % or more of themetaxylylenediamine unit.
 12. The polyamide resin composition of claim3, wherein the polyamide (X) comprises 80 mol % or more of the adipicacid unit.
 13. The polyamide resin composition of claim 5, wherein thepolyamide (X) comprises 80% or more of the sebacic acid unit.
 14. Thepolyamide resin composition of claim 1, wherein ([COOH]—[NH₂]) is in arange of 20 to 70 μeq/g.
 15. The process of claim 7, wherein an amountof the alkali metal compound (C) is in a range of 0.5 to 1 in terms of avalue obtained by dividing a mole number of the alkali metal compound(C) by a mole number of the phosphorus atom-comprising compound (B). 16.The process of claim 8, wherein, in (b1), 94 to 98 parts by mass of thepolyamid (X) and 6 to 2 parts by mass of the alkali compound (A) aremolten and kneaded.
 17. The process of claim 8, wherein, in (b2), 1 to 5parts by mass of the polyamid master batch (Y) and 99 to 95 parts bymass of the polyamid (X) are molten and kneaded.